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December 2022

SPARTA President’s Corner

contributed by Randy Springs

As we enter the final month of 2022, we should take advantage of available time off to rest and reflect with family and friends. My retirement has given me a new perspective on work/life balance. Pressure to meet deadlines and upgrade schedules along with handling emergent issues at work should invoke more priority to using time away for relaxation. I hope that the coming holiday season provides that for us all.

This month, we will again be holding our SPARTA meetings via Zoom format. With the removal of mask mandates in NC, we can consider going back to our in-person meetings if we can find an appropriate venue. Let us know if you have any suggestions for a meeting location.

For our December meeting, join us for a presentation from Chris Taylor of 21st Century Software, who will update us on the latest enhancements to the IBM Change Tracker for z/OS. Invite your fellow systems programmers to join us for networking and information.

Please join your colleagues online at 7 p.m. on Tuesday, December 6, on Zoom. Watch for meeting connection information coming your way soon.

Randy Springs
Retired (Truist)

Future Speakers (subject to change)

December 6, 2022 - New! IBM z/OS Change Tracker for z/OS 2.5 by Chris Taylor of 21st Century Software

January 3, 2023 - No meeting! Happy Holidays!

February 7, 2023 - TBA by TBD

We need ideas and volunteers for future speakers. Presentations don’t have to be fancy, just informative and interesting. Even a 5 or 10 minute talk can start an interesting interaction. Contact Ron Pimblett by phone as noted below.

2022-2023 SPARTA

Board of Directors

Randy Springs - President

Retired (Truist)                  (919) nnn-nnnn


Raleigh, NC 27604

Ron Pimblett - Vice President

MDI Data Systems

Land line 613 599 6970

Mobile 613 981 6919

190 Guelph Private

Kanata, ON K2T 0J7

Chris Blackshire - Secretary

Retired (Dell, Perot Systems, Nortel)  (919) nnn-nnnn


Durham, NC 27713

Randy Springs - (Acting) Treasurer

Retired (Truist)                  (919) nnn-nnnn

see Randy

Springs earlier

Ed Webb -  Communications Director

Retired (SAS Institute Inc.)  (919) nnn-nnnn


Apex, NC 27523

Mike Lockey -  Web Master

Guilford Co. Information Services  336-641-6235

201 N. Eugene St.

Greensboro, NC 27401


Coronavirus Change: All meetings for the foreseeable future will be held online at 7 p.m. via the Zoom App. The link to meeting is sent to SPARTA Mailing list within 24 hours of the meeting time for security reasons. Stay safe.

Meetings are scheduled for the first Tuesday evening of each month (except no meeting in January), with optional dinner at 6:15 p.m. and the meeting beginning at 7:00 p.m.

These monthly meetings usually are held at LabCorp’s Center for Molecular Biology and Pathology (CMBP) near the Research Triangle Park (see last page). Take I-40 to Miami Boulevard and go north. Turn right onto T.W. Alexander Drive. Go about a mile or so. Then turn right into LabCorp complex and turn Left to the CMBP Building (1912 T.W. Alexander Drive). In the lobby, sign in as a visitor to see Bill Johnson. Bill will escort you to the conference room.

Call for Articles

If you have any ideas for speakers, presentations, newsletter articles, or are interested in taking part in a presentation, PLEASE contact one of the Board of Directors with your suggestions.

Newsletter e-Mailings

The SPARTA policy is to e-mail a monthly notice to our SPARTA-RTP Group. The newsletter is posted to the website about five (5) days before each meeting so you can prepare. The SPARTA distribution List is maintained by Chris Blackshire; if you have corrections or problems receiving your meeting notice, contact Chris at

August 2022 “CBT Tape” Shareware Online

The directory and files from the latest CBT tape V504 (dated August 16, 2022) are available from

If you need help obtaining one or more files, contact Ed Webb (see Board of Director’s list for contact info).

Minutes of the November 1, 2022 Meeting

• The meeting was called to order at 7:05 PM by Randy Springs, the SPARTA President.

• This Twenty-ninth (April 2020 to November 2022) virtual SPARTA meeting was held via the Zoom Software.

• Fourteen (14) people were present at the virtual meeting.

• The business portion of the meeting was followed by the presentation.

• For the Roundtable, everyone introduced themselves, told where they worked, talked about working from home, and briefly described their job functions and what they've been doing at work and home.


• The minutes of the October 4, 2022 cancelled meeting as published in the November 2022 Newsletter were approved.

• The October 31, 2022 Treasurer's report (there was No Activity in October) as published in the November 2022 Newsletter was approved. As of October 31, 2022, the current balance was $994.51.

• Call For Articles: Articles are needed for this newsletter. If you would like to write an article for this newsletter, please contact Ed Webb. Keep in mind that you don't really need to write the article, it can be an article that you read that you would like to share with the membership.

• The SPARTA Web page is available at this site: Please send any comments or suggestions about the Web page to Mike Lockey. Be sure to check the Web page every once in a while to see any new or changed information.

• 2022 meeting dates, Future Speakers and Topics (subject to change based on internal politics, budget, the weather):





December 6, 2022

21st Century Software

Chris Taylor

Introducing IBM z/OS Change Tracker for z/OS 2.5

If you have suggestions about speakers and topics, contact Ron Pimblett.

• The next SPARTA monthly meeting will be held virtually on Tuesday, December 6, 2022.

• The annual dues have been suspended (motion passed in the March 2021 monthly meeting).

• Thanks to Randy Springs for online hosting the November 1 meeting via Zoom.

• There are currently 100 people on the SPARTA e-mail distribution list.

• Send any e-mail address changes to Chris Blackshire so he can update the SPARTA distribution List. The SPARTA meeting notices are being sent via a simple distribution list maintained by Chris.

• Randy Springs is looking for a new Treasurer volunteer. He projects about 2 hours per month is needed.
- Contact Randy Springs if you are interested.

• Randy Springs has setup a SPARTA group on LinkedIn. Please join.

• There was discussion about a possible 2023 in person meeting, depending on vaccinations and room availability. Stay tuned.
- LabCorp Future Meeting Place: No update from Bill Johnson.


• We will continue meeting virtually for now with a future in-person meeting date TBD. Stay tuned.
• Randy will contact Bill Johnson to determine the LabCorp meeting place status.
• The Business portion of the meeting and the meeting itself ended about 8:25 P.M.

• The Presentation started at 7:15 PM.

• Presentation Topic: Insights into New XCF Path Usage Metrics

by Frank Kyne of Watson & Walker and Todd Havekost of IntelliMagic

• Agenda
Introduction to XCF Signaling and Transport Class Simplification
Managing MAXMSG Values
New Path Usage Concepts
Analyzing New Path Usage Metrics
Summary / Resources / Questions

The online presentation ended at about 8:10 PM.

• Presentation Access - See Below for a full outline of the presentation.

See the SPARTA webpage for all recent presentations including this one.

Co-Speaker Contact Info:
Speaker: Frank Kyne
President Watson & Walker
Phone +1-845-309-2956

Speaker: Todd Havekost
Senior z/OS Performance Consultant for IntelliMagic

• The November 1, 2022 monthly meeting ended about 8:25 P.M.

Treasurer’s Report for November 2022

contributed by Randy Springs

The balance in the account is $994.51 as of November 30, 2022.

SPARTA Financial Report
11/01/2022 through 11/30/2022


Opening Balance 11/1/2022


Total Deposits

Food money donated











Web Site


Petty Cash


Bank Service Charges






PETTY CASH on hand




Items of Interest

SPARTA Schedule and Menu for 2022

contributed by Chris Blackshire

Dec 6, 2022 - BarBQ
Jan. 3, 2023 - No meeting!

SHARE 2023 Atlanta Hotel and Registration Are Now Available!

contributed By Ed Webb

"Join us at SHARE Atlanta, March 5-8, 2023, at the Hyatt Regency Atlanta. Get ready to experience days of unmatched education, in-person technical sessions, and the opportunity to connect with an influential group of IT professionals representing the world's top tech organizations."

Early Registration for this in-person short-week SHARE Conference ends on Friday, January 6, 2023. The hotel cut-off date for reservations is Friday, Friday, February 3, 2023, or whenever rooms sell out, whichever occurs first.

Details on Registration and Hotel and Travel are available at SHARE Atlanta.

IBM z/OS V2.5 4Q 2022 enhancements

contributed By Ed Webb

"Capabilities delivered in the z/OS V2.5 4Q update include the following items. Many of these items are also available in prior releases with continuous delivery (CD) and are noted as such:

IBM SMF Explorer with Python. This new feature enables applying data science and AI against System Management Facilities (SMF) data in order to gain insights and decision velocity.

Remove temporary catalog aliases. z/OSMF Software Management enables software installers to disconnect a new master catalog created when installing z/OS V2.5 from the driving system catalog. This follow-on support completes the process of creating a new master catalog when installing z/OS.

z/OS Management Facility (z/OSMF) enhancements. Numerous features are delivered, including new REST APIs for expanded job notifications and storage management, z/OSMF desktop improvements to download or upload files and data sets, and added security validation of z/OSMF nucleus and Security Configuration Assistant (SCA).

JES2 job notifications. Enhancements provide additional HTTP job notifications to help simplify the progress tracking of a z/OS job.

z/OSMF Software Management reporting REST API. z/OSMF Software Management has enabled new REST APIs to perform often-used software maintenance report actions.

Communications Server exploitation of the IBM Function Registry for z/OS. Enhancements to regularly store information about the maximum number of SNA applications and sessions in the IBM Function Registry have been added.

Other enhancements include DFSMS zHyperLink write support for multivolume data sets, IBM Customized Offerings Driver enhancements, RACF® Password Phrase interval support, and IBM WebSphere® Hybrid Edition 5.1 support.

Read the IBM Announcement Software 222-347 dated November 15, 2022 for details.

Blockchains, What Are They Good For?

Contributed by Ed Webb

Are you too young to know the answer to the question? Paul Krugman, Nobel Prize winner for Economics and New York Times columnist, asks this question, and some harder questions in one of his columns this week of December 1.

"...the prices of crypto assets have plunged, while a growing number of crypto institutions have collapsed amid allegations of scandal. The implosion of FTX, which appears to have used depositors’ money in an attempt to prop up a related trading firm, has made the most headlines, but it’s only one entry on a growing list.

We are, many people say, going through a “crypto winter.” But that may understate the case. This is looking more and more like Fimbulwinter, the endless winter that, in Norse mythology, precedes the end of the world — in this case the crypto world, not just cryptocurrencies but the whole idea of organizing economic life around the famous “blockchain.”

And the real question, it seems to me, is why so many people — not just naïve small investors, but also major financial and business players — bought into the belief that this bad idea was the wave of the future."

Paul Krugman explains how crypto-collapse and its blockchain underpinnings affects our favorite mainframe company in this thoughtful column.

And the answer to the original question: Absolutely Nothing! [from the song War by Edwin Starr about 1969]


Adults Are Revealing Things They Like Less The Older They Get, And It's More Than A Little Dark

contributed by Chris Blackshire

Look, we all know that growing up is a massive trap, but nowhere is it as obvious as when you find yourself getting older and starting to hate the things you loved as a child.

A reader recently asked, "What are you starting to like less and less the older you get?" Here are a few grown-ups sharing some examples.

1. Someone opening an Instagram or TikTok video on loud volume out of nowhere. Whether it's on the train or on the sofa, it makes me scream inside.

2. Making appointments for my dog, myself, my kids, etc. You have to start a new patient portal, then verify your email. Then, you have to try to make an appointment through their portal, but the portal is down for maintenance. So you call, and you're sent to electronic voicemail, which recommends an online portal. Rinse and repeat. Eventually, you find the right formula to speak to a human, and they're not accepting new patients or there are no openings for 10 weeks.

3. Social media. I hate what it does to people, and I hate the things it makes people do so much. It used to be useful once upon a time, but now, social media is just a cesspool of the worst kinds of people.

4. Birthdays. Getting older to reach adulthood was fun. Getting older to reach being a senior citizen is less fun.

5. Sweetness. The older I get, the less I can tolerate sweet stuff. I used to need a lot of sugar in my coffee; now, a dash of sugar is enough, and if need be, no sugar is fine, too.

6. Nobody seems to remember when using speaker phone to talk was considered rude/low class. Also, video calls in general. If it's not urgent, just text, voice record, or voice call in that order. Text preferably, and don't expect me to listen to voice recordings until I am somewhere private (since they play through the speaker by default). Randomly demanding both my ears and eyeballs for simple communication when I am busy is gonna be an instant call reject + text message saying I can't talk.

7. Home. I moved far away and made my own life. In the beginning, I was desperately attached to my home and missed it to the core of my being. Now, I realize that I left problems behind that I'll never have to face again. Every visit makes me more confident in my decision. I wish the best for my friends and family, but I'm glad I got out.

8. Crowded areas. I went to the grocery store yesterday, and I felt uncomfortable with that many people around.

9. I hate getting drunk now. Even by the end of the night, I just feel exhausted and sick; then, the following day is always such a waste. I can’t be bothered anymore.

10. Summer. I realized I only loved it because of summer break and my birthday. Summer absolutely sucks! It’s warm as hell outside, and every birthday after 21 has been one year closer to old age.

11. Since I haven’t seen it yet: soda and other soft or carbonated drinks. They’re so sugary and awful; it’s like I can imagine my teeth dissolving and my insides corroding just from drinking a bit of it. I don’t hate it with a passion, and on a social occasion, I might even drink some, but I always feel bad afterward and sometimes even sick. Water is love; water is life.

12. Loud restaurants. I don't understand why places have the music cranked so loud that you can't even hear yourself talk. Seriously, who's enjoying that?!

13. Dating apps. Not only have I aged out of them, but now, it's been active people using it for follower clout chasing. Don't get me wrong, they're great when they work. But when they don't, which is very often, they're exhausting.

14. How quickly things break down. Everything is cheaply made so you will have to replace it quickly. My grandmother had the same oven for 50 years, and a fridge that was easily 30 years old.

15. Gossip. I used to be a fiend for gossip. I don't care, unless it involves me or benefits me. I just don't care.

16. Rude people, especially middle-aged and elderly people who think they can get away with being rude just because of their age. I hate these people as much as I did when I was a young person.

17. The acquisition of things. The first half of my life was all about building the nest and feathering it. Now, I’m divesting everything I don’t absolutely need. No storage unit now, nothing in the attic, the garage actually holds the car. The end game is to have a near-zero footprint of 'stuff.'

18. Online gaming. Everyone is just toxic or childish, and it gets old. I try to stay away from them now and just play single-player stuff.

19. Shopping. As a kid and teenager, there was a bunch of stuff I couldn’t have, so when I started earning money, I was really enjoying buying something if I wanted to. Now, I just think that constant online shopping and the throw-away-and-repurchase-cycle makes you feel empty on the inside and hurts the environment. I’d rather have kind people and joy in my life than things.

20. Work. I remember the naive motivation I had to get old, jump into the workforce, and make my own money. I’ll gladly go back in time and go back to begging my parents for rides to places and new shoes again.

21. Cynicism. Humans are cute, things are good, flowers exist, that person who’s a huge grouch at work might actually be cool once you get to know them.

22. Traveling. As a kid, traveling is almost always a fun vacation. I dreamed of having a job that let me travel. Now, I’m almost 30 and have a travel-centric job, and going to the airport is anxiety-inducing because it’s always such a miserable experience.

23. Screens. The omnipresence of smartphones and TVs is really taking a toll on everyone's mental health, attention span, and social skills. People are addicted and don't seem to notice or care about it. I've been looking at screens less and less. Now, sitting down to look at the sky or read a book (as well as getting off social media and abolishing caffeine from my life) has diminished my anxiety so much that I feel in some ways I've re-learned how to think.

24. A lot of food. I mean I've always been a picky eater, but the older I get, the worse it gets. Sometimes, it's because of texture; sometimes, it's just the taste itself.

25. Movies with gratuitous violence. I just can't stomach it anymore. Occasionally, there's a movie that's about gratuitous violence and depicts it in a way that adds to the story, but violence for its own sake just depresses me. I especially hate when it's really wacky comedy mixed with graphic violence. Pick one or the other.

Membership Information

Don’t Forget the Next SPARTA Meeting

Tuesday, December 6, 2022

7 p.m.

Location: Online

Information about access to our online meeting will be sent to our e-mail list by Tuesday, December 6.

Free Food before meeting: Your Food at Your Home


Introducing IBM z/OS Change Tracker for z/OS 2.5


Chris Taylor of 21st Century Software

SPARTA Corporate Sponsors:

DTS Software

Rocket Software

Software Diversified Services


November 2022 Presentation outline

• Presentation Topic: Insights into New XCF Path Usage Metrics

by Frank Kyne of Watson & Walker and Todd Havekost of IntelliMagic

• Agenda
Introduction to XCF Signaling and Transport Class Simplification
Managing MAXMSG Values
New Path Usage Concepts
Analyzing New Path Usage Metrics
Summary / Resources / Questions

Introduction to XCF Signaling and Transport Class Simplification

XCF Basics

- XCF provides high speed resilient messaging between peer programs running on the same or different systems in the sysplex. We generally find 50-100 exploiters per system.
- XCF typically uses CF structures to provide paths from each system to every other system in the sysplex, with buffers at each end of each path to ensure smooth and timely flow of messages.
- A key concept in XCF is that, from XCF’s perspective, signaling paths are point-to-point and uni-directional.
- - For example, even though a CF structure enables every-to-every 2-way communication, you still define PATHIN and PATHOUT separately in your COUPLExx member of Parmlib.
- - And all XCF signaling reporting is on the basis of activity between a pair of systems.

Intro to Transport Class Simplification

- In z/OS 2.4, IBM delivered enhancements to XCF called Transport Class Simplification (TCS).
- - This enhancement is ENABLEd by default, and no changes to your definitions or infrastructure are required.
- - The implementation was so effortless that many customers didn’t even notice the change.
- To understand how TCS ‘Simplified’ things, let’s have a quick look at how XCF signaling worked before TCS, and how it works now.

Life Before TCS

- Because XCF supports message sizes from 1 KB up to 61 KB, and CPC memory was MUCH smaller when XCF was introduced (c. 1990), XCF provides a way to group paths (‘transport classes’<), and optimize the size of each buffer for each transport class (‘CLASSLEN’).
- - It also lets you control the maximum amount of memory that can be used by each path’s buffer pool (MAXMSG).
- XCF generally used the message size to assign each message to a specific transport class.
- Because signaling resources were divided into multiple transport classes, the system programmer (in theory) had to:
- - Identify the volume of messages of each size.
- - - Not easy because the only way to see the number of each sized message is using D XCF,CD,CLASS=ALL commands (this info is not in SMF).
- - Take into account that message volumes and mix of sizes varied by time, day, and system.
- - - This info IS in SMF, however it is reported separately for each pair of systems
- - - - there are no XCF sysplex-level SMF records.
- - With that info, identify how many paths and buffers were needed for each subset.
- - Then define that configuration in the COUPLExx Parmlib member.
- This is a very time-consuming exercise.
- - It is probably impossible to have static definitions that were always perfect for every system in a constantly-changing environment. And because of the number, format, and inter-relationship between the definition statements, it is not unusual to find definition mistakes.

Life Before TCS (2-way sysplex) (Diagram not copied)

How Transport Class Simplification Helps

- The ‘Transport Class Simplification’ enhancement is intended to let XCF pool your signaling resources, using your existing definitions, and manage them dynamically.
- - Rather than certain message sizes being limited to a given transport class and its associated resources, any XCF message can potentially be sent on any XCF path.
- - - This significantly increases the amount of storage that is available for messages of a given size.

Life After TCS (Diagram not copied)

Life After TCS

- Because any message can potentially use any path, you no longer need to worry about the breakout of message sizes.
- All you need to do is to ensure XCF has enough paths and buffers to handle the overall messaging workload, and then leave it to XCF to manage those resources.
- Because of the traditional method of dividing XCF signaling resources across multiple transport classes, each sized to handle its own peak traffic, most sysplexes have more paths and buffers than they really need.
- This presents opportunities for optimization – Todd will be describing how the new XCF RMF metrics can help you with that.
- However, it also increases the possibility of excessive storage consumption in extreme circumstances in systems with huge MAXMSG values.

Managing MAXMSG Values

Finding Appropriate MAXMSG Value

- Traditionally, it was considered a ‘bad thing’ if XCF ran out of buffers (reported in an RMF PP XCF Path Activity report as ‘BUFFERS UNAVAIL’):
- - The normal response to this was to increase the maximum size (MAXMSG) of the buffer pool for that PATHIN.
- However, incremental improvements to XCF over the years have reduced the seriousness of that situation, meaning that very large buffer pools generally are not required.
- Also, the real reason for trying to minimize the number of times XCF ran out of buffers was to avoid a performance impact to XCF exploiters.
- - However, there was no way to accurately identify that impact, so the only available course of action was to increase the MAXMSG.
- Let’s see how TCS and related new metrics have changed this.
- As we saw, when TCS is enabled, all incoming messages now reside in 64KB buffers.
- - For small messages, which typically make up about 90% of messages, this is an 11x increase in storage for each message.
- Normally, messages arrive and are retrieved by the target address space very quickly, so the extra few KB are irrelevant.
- But what happens if the target address space is slow or stopped or just can’t keep up with the message arrival rate?
- 2-Way Sysplex (Diagram not copied)
- 10-Way Sysplex (Diagram not copied)

Finding Appropriate MAXMSG Value

- Why do we care?
- Incoming and outgoing XCF messages (plus other XCF control information) reside in a 2GB XCF data space while waiting to be retrieved or sent.
- If there is a flood of messages and the maximum buffer pool sizes are very large and messages are not being moved out of the buffers, it is possible for XCF to consume all the storage in its data space – this currently results in a 0A2-040 wait state (see open HIPER APAR OA62980).
- - Additionally, if XTCSIZE is enabled, the PATHIN buffers that used to reside in 31-bit real storage, are now placed in above the bar 64-bit real. This was delivered by HIPER APAR OA60480.
- To protect systems from this risk, IBM issued the following guidance:
- - Aim to have PATHIN MAXMSG values not greater than 2000.
- - Total PATHIN MAXMSG values should be < 800,000.
- How to determine your Total PATHIN MAXMSG value?
- Fastest way is to use D XCF,PI,STRNM=ALL command:
- - Make sure you get this info for EVERY connected system.
- What to do if you find your PATHIN MAXMSGs add up to much more than 800,000?
- - If increasing MAXMSG was the traditional way to address No Buffer conditions, will decreasing MAXMSG not increase # of No Buffer?
- Maybe, but will anyone notice? Luckily, the new metrics have that covered! There are two new fields in the 74.2 SMF record:
- - Count of number of no buffer conditions that actually resulted in a message being delayed.
- - Total delay time for those messages.
- Impactful No-Inbound-Buffer Conditions (Diagram not copied)
- If you want/need to reduce your MAXMSG values:
- - Check your current Impactful No Buffer counts and times.
- - You can adjust MAXMSG values dynamically – SETXCFMODIFY,PI,STRNM=whatever,MAXMSG=some_smaller_value
- -The scope of this command is a single system. It needs to be issued on every system where you want to make the change.
- - Keep an eye on the Impactful No Buffer values as you go along.
- - It is not necessary to adjust the PO and PI values at the same time
- - - we recommend leaving PO MAXMSG values as they are until you are finished adjusting PI MAXMSG values.

Managing MAXMSG

- IBM’s experience has been that excessive memory usage on the sending side (transport class and PATHOUT) is very uncommon.
- It is very unlikely that every XCF exploiter on a given system will suddenly spring to life and bombard their peers on every other system.
- The exception is if a system dies but is not partitioned from the plex in a reasonable time – XCF will continue accepting messages for that system until it is removed from the sysplex, but is unable to send them – so they will starting queueing in the PATHOUT buffer pools.
- - Recommendation: Follow IBM Best Practice and ensure that BCPii and SSDPP are enabled.


- TCS is great – don’t disable it!
- - Apply the PTF for OA60480 if not already applied.
- - - Subscribe to HIPER APAR OA62980 and apply when available.
- - - Aim to get the sum of PATHIN MAXMSGs under 800,000.
- - - In normal running, keep an eye on Impactful No Buffer times.
- - - - Let us know if they become ‘uncomfortable’.

New XCF Path Usage Concepts

Rationale for New Path Usage Metrics

- With TCS no longer need to manage transport classes
- New metrics designed to inform remaining configuration items
- - Number of paths
- - Number of buffers
- Prerequisites that have not changed
- - Good performance on all systems across the sysplex processing messages
- - Good performance on signaling paths (typically CF list structures in today’s environments)

XCF Path Utilization

- Measured on inbound side
- Signals are read in parallel in “buckets” of up to 4 signals
- XCF reports “utilizations” as discrete values of
- - 25% - 1 read active
- - 50% - 2 reads active
- - 75% - 3 reads active
- - 100% - 4 reads active
- A bucket ends when the I/O completes for all “N” signals in the current bucket

“Buckets” and “Windows”

- XCF also measures total time spent in a path utilization “window”
- Assuming an idle path, a window begins when a bucket of N reads is started
- That window continues as long as another N reads are initiated at the end of the current bucket
- A window ends when the value of N changes
- - If N=0, the path has become idle
- - A different N>0 starts a new window at the new utilization
- - Buckets and Windows – Illustrated (IBM) (Diagram not copied)

RMF Path Usage Statistics Block (x4) (Table not copied)

Calculated Timing Metrics

- Path utilization = sum(TimeSum fields for all 4 blocks) / interval
- For each of the 4 utilizations (25/50/75/100)
- - Time per bucket = TimeSum / (SigCnt / (Percent / 25))
- - - Percent / 25 = number of active reads for that utilization
- - Time per window = TimeSum / Time#
- - Time per read = TimeSum / SigCnt

Analyzing New Path Usage Metrics (All Diagrams not copied)

• Sample RMF Report diagram (IBM)
• Time per Bucket by Utilization diagram
• Time per Bucket by Utilization with Inbound Signal Volume diagram
• Time per Bucket by Utilization diagram
• Time per Bucket by Utilization with Inbound Signal Volume diagram
• Timing Metrics at 50% Utilization diagram
• Timing Metrics at 100% Utilization diagram
• Count Path in Use at 100% Utilization diagram
• Counts Path in Use by Utilization diagram
• Counts Path in Use by Utilization diagram
• Time per Read by Utilization diagram
• Path Utilization diagrams
• Time per Bucket at 25% Utilization diagram
• Coupling Facility Asynchronous Service Time diagram


Cheryl Watson’s Tuning Letter

- XCF series of articles
- - Transport Class Simplification – Tuning Letter 2020 No. 2
- - XCF: A Reliable (But Often Overlooked) Component of Sysplex – TL 2022 No. 2
- - Using New XCF Metrics to Optimize XCF Buffer Use (Part 1) – TL 2022 No. 3
- - [Article 4 in XCF series] – TL 2022 No. 4
- To receive reprints of IntelliMagic written articles in the Tuning Letter contact:

Additional Information

- SHARE in Columbus 2022 session Parallel Sysplex Update, by Mark Brooks.
- z/OS MVS Setting Up a Sysplex, SA23-1399.
- IntelliMagic zAcademy webinar Insights Into New XCF Path Usage Metrics, by Todd Havekost and Frank Kyne.
- - zAcademy sessions are available on-demand at
- - For additional information, please contact

The online presentation ended at about 8:10 PM.