I would suggest starting with the IEA_ASIDS health check.
For example, on one of our test systems:
SDSF OUTPUT DISPLAY IEA_ASIDS LINE 0 COLUMNS 02- 16
COMMAND INPUT ===> SCROLL ===> CSR
******************************* TOP OF DATA *********************************
CHECK(IBMSUP,IEA_ASIDS)
SYSPLEX: UTCPLXJ8 SYSTEM: JC0
START TIME: 03/14/2024 12:42:18.542848
CHECK DATE: 20060418 CHECK SEVERITY: LOW
CHECK PARM: NORMAL(5%),REPLACEMENT(5%),DAYSUNTILIPL(1)
IEAVEH010I
Summary of ASID availability
ASIDs Limit Avail InUse Total
Normal 150 2499 501 3000
Replacement 5 95 5 100
IEAVEH061I The system has been IPLed for between 2 and 3 days. On the
average 2 ASIDs have become non-reusable per day. At the current rate of
depletion, the system will run out of ASIDs in 1297 days.
IEAVEH012I Permanently non-reusable ASIDs by jobname
C2PACMON (3)
DRLJSMFX (1)
AVZC (1)
IEAVEH001I Permanently non-reusable ASIDs by ASID
ASID: 0215 Jobname: C2PACMON
ASID: 01F8 Jobname: C2PACMON
ASID: 0199 Jobname: DRLJSMFX
ASID: 0178 Jobname: AVZC
ASID: 013B Jobname: C2PACMON
END TIME: 03/14/2024 12:42:18.543247 STATUS: SUCCESSFUL
Jim Mulder
----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of
Alan Haff
Sent: Thursday, March 14, 2024 12:08 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: ASVT & ASID discrepancy mystery
We had an outage on one of our development systems earlier this week due to
lack of available ASIDs.
After I freed up some ASIDs and was able to get logged on, I ran Mark Zelden’s
ASIDLIST program (file 434 on the CBT tape). The results were… weird (to me,
anyway). The program walks through the ASVT and lists out each ASCB and whether
it’s available, non-reusable, or its jobname.
At the end of the run, the program lists the total number of address spaces it
found, how many of them that are in use, how many of them that are
non-reusable, and a calculation of the number that are available (total minus
in-use minus non-reusable).
TOTAL ADDRESS SPACES IN THE SYSTEM: 860
TOTAL ACTIVE ADDRESS SPACES IN THE SYSTEM: 143
TOTAL AVAILABLE ADDRESS SPACES IN THE SYSTEM: 673
TOTAL NON-REUSABLE ADDRESS SPACES IN THE SYSTEM: 44
Looks all good right? From this you’d think there would be plenty of available
address spaces – 673.
But here’s where it gets weird. The program also displays the values from the
ASVT itself and for some reason, the value of ASVTAAV (“NUMBER OF FREE SLOTS
ON THE ASVT AVAILABLE QUEUE” – see SYS1.MODGEN(IHAASVT)) says that only 9 ASIDs
are available:
ASID USAGE FROM ASVT
MAXUSER FROM IEASYSXX: 500
IN USE ASIDS: 491
AVAILABLE ASIDS: 9
RSVSTRT FROM IEASYSXX: 10
RSVSTRT IN USE: 0
RSVSTRT AVAILABLE: 10
RSVNONR FROM IEASYSXX: 350
RSVNONR IN USE: 44
RSVNONR AVAILABLE: 306
NON-REUSABLE ASIDS : 44
At that point I decided to throw in the towel and re-IPL.
I don’t know anywhere near enough about z/OS internals to be able to explain
the discrepancy I found. Maybe it makes more sense to someone here. Any
thoughts?
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