PH48809: ABEND ABN= 402-00000000,C=MQ900.920.CHIN,M=CSQXSUPR,LOC=.........????????+07F00 AND HANG DURING CHINIT SHUTDOWN

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The 402 abend occurs due to an attempt to post an ECB in
  unavailable storage - the storage address is actually
  x'C3888195' = 'Chan', and is part of the CSQX599E message
  issued immediately before the abend occurred.
  
  The problem appears to be that CSQXSRVR has queued a QSPL to
  the adapter tasks, but then returned early with CSQX_NO_SERVERS
  due to the qmgr having been killed. The QSPL contains pointers
  to storage in CSQXADPM (the caller of CSQXSRVR)'s automatic
  storage. When CSQXSRVR returns early, CSQXADPM also returns (in
  this case reporting the failure of MQBACK due to
  MQRC_CONNECTION_BROKEN), and the automatic storage is
  subsequently reused.
  
  When chinit termination calls CSQXADPC on the supervisor task
  later, routine Cancel_QRPLs attempts to post any outstanding
  QRPL's queued to the adapters, based on the queue of QSPLs.
  When it gets to the QSPL from the CSQXADPM/CSQXSRVR call
  mentioned above, QSPL.pItem points to an area of reused
  automatic storage that previously held the ECB address.
  Depending on the contents of this storage, the ?post macro
  could either succeed (overlaying the storage addressed by the
  new value) or abend 402 if the storage is inaccessible.
  
  In the latter case, as the supervisor had not yet finished
  notifying other tasks to end, CSQXJST ends up waiting
  indefinitely, causing the termination to hang.
  .
  Additional symptoms and keywords:
  ABEND402 ABENDS402 STOP CHINIT potential overlay
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Various problems can occur when the     *
  *                      channel initiator shuts down as a       *
  *                      result of abnormal queue manager        *
  *                      termination, including                  *
  *                      - abend 402-00000000                    *
  *                      - abend 702-00000014                    *
  *                      - channel initiator hang during         *
  *                        termination                           *
  *                      - high CPU in channel initiator during  *
  *                        termination                           *
  ****************************************************************
  When the channel initiator queued a request to the adapter tasks
  it attempted to find a suitable adapter to process the work, and
  resumed it. However the resume request failed due to the adapter
  tasks terminating because the queue manager had terminated
  abnormally.
  CSQXSRVR reported the MQRC_CONNECTION_BROKEN, however the
  request remained queued.
  Later on in chinit termination processing CSQXADPC dequeued the
  request and posted it, however as the storage containing the ECB
  had subsequently been reused, the ?post macro abended S402.
  Depending on how the storage was reused, other abends can be
  seen, for example S702, and/or CSQXADPC can enter a loop
  condition that results in high CPU and chinit termination
  hanging.
  

Problem conclusion

• CSQXSRVR is changed to wait for the ECB to be posted by chinit
  termination before returning, so that the storage containing
  the ECB will not be reused prior to being posted.
  

Temporary fix

Comments

APAR Information

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

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

  UI92265

Modules/Macros

• CSQXSRVR
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R200 PSY UI92265

     UP23/07/15 P F307

Fix is available

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