PI56990: TITLE: CSQ1,ABN=5C6-00E50002,U=SYSOPR ,C=W9700.800.ASMC- CSQVUNLX, M=CSQVLFRR,LOC=CSQMLPLM.CSQMREF1+00000B2E

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The customer is running WebSphere MQ for z/OS V8.0 when QMGR
  CSQ9MSTR abended with the following:
  .
  TITLE: CSQ1,ABN=5C6-00E50002,U=SYSOPR  ,C=W9700.800.ASMC-
  CSQVUNLX,M=CSQVLFRR,LOC=CSQMLPLM.CSQMREF1+00000B2E
  .
  Looking at the PSW 077C1001 236E7466, the actual abend
  5C6-00E50002 is produced in Csect CSQVXUL0 (BASE) at offset
  x'6B4'. The '00E50002'X means, "UNLATCH REQUEST AND LATCH NOT
  OWNED BY REQUESTING EB". According to the code, the following
  are contained in the regs at time of abend:
  .
  R2  = XCLASSNO  0000002B (LPVT)
  GR3 = XLTCHPTR 59F7F768
  .
  MSTR trace is enabled but only contains a few enteries for the
  EB 20AB0F18 (212.MMCLTRX). I found APARs PI19991/UI20637 and
  PI47734/UI30746 that mentioned 00E50002 but did match this
  module and offset. The APARs do appear to be applied.
  .
  The change team reviewed the dump and determined the abend
  occurs due to an IVSA being reused while still in use by
  CSQMREF1. Trace shows that CSQICDSQ was called due to the
  deletion of queue LG62SD03278C8C0905DA9 on another qmgr in the
  qsg. CSQICDSQ called CSQMCSQF to close the connection to the
  queue, and this queued the close request to the structure task.
  However there was a significant delay (several seconds) before
  this request completed but it's not clear from the trace what
  caused this delay.
  While this request was pending the list transition exit
  detected a transition for this queue and CSQMREF1 was called to
  process it. CSQMREF1 suspended waiting for the IVSA latch,
  which was held by the deleting task.
  When the close request completed, CSQMCSQF released the latch
  and CSQMREF1 obtained it. CSQICDSQ then released the IVSA,
  which contains this latch, and the IVSA was then used by
  another queue. When CSQMREF1 subsequently attempted to release
  the IVSA latch, it abended because the latch no longer appeared
  to be held (due to it now being associated with a different
  queue). It appears that there is insufficient serialisation
  between list transitions and CSQICDSQ.
  .
  Additional Symptoms:
  ABEND S0C4
  ABN=0C4-00000011 CSQERCAT+000009FE
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 8 *
  *                 Release 0 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Various abends occur when a shared      *
  *                      queue is deleted on a different queue   *
  *                      manager in the queue sharing group, and *
  *                      the local queue manager is processing a *
  *                      list transition for the queue.          *
  *                                                              *
  *                      Symptoms can include:                   *
  *                      - Abend 0C4 in CSQMLTR0                 *
  *                      - Abend 5C6-00C5101A in CSQEBMON        *
  *                      - Abend 5C6-00D40025 in CSQMLTR0        *
  *                      - Abend 5C6-00E50002 in CSQMREF1        *
  *                      The abends are followed by abnormal     *
  *                      queue manager termination 6C6 with      *
  *                      REASON=00E50702                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Insufficient serialisation between list transition exit
  processing for a shared queue and shared queue deletion
  processing can allow CSQICDSQ to free the IVSA for a shared
  queue that has just been deleted on another queue manager in the
  queue sharing group, while a list transition is being processed
  for that shared queue.
  Depending on the type of list transition being processed, and
  how quickly the freed IVSA is reused by another queue, this can
  lead to several different abends occurring in list transition
  processing.
  The abnormal termination of the SRB processing the list
  transition is unexpected, and results in the queue manager
  terminating abnormally.
  

Problem conclusion

• The serialisation between shared queue deletion and list
  transition processing is improved to prevent the IVSA being
  freed while still being used by list transition processing.
  000Y
  CSQELTRX
  CSQICDSQ
  CSQIEXP2
  CSQMLTRX
  CSQMLTR0
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI40384

Modules/Macros

• CSQELTRX CSQICDSQ CSQIEXP2 CSQMLTRX CSQMLTR0
  

Fix information

• Fixed component name

  WMQ Z/OS 8

• Fixed component ID

  5655W9700

Applicable component levels

• R000 PSY UI40384

     UP16/09/20 P F609 ¢

Fix is available

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