PI14456: CSQ1,ABN=5C6-00E2000B,U=XXXXXX,C=R3600.710.ASMC-CSQVICEU, M=CSQVEUS2,LOC=CSQSLD1.CSQSFBK+00000DDA - BUILDUP OF ITRQP CBS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The customer is running WebSphere MQ V7.1 and they are
  receiving the 5C6-00E2000B. This has occurred due to the queue-
  manager going short on storage due to the problem with the
  ITRQP control blocks associated with a specific queue. These
  ITRQP control blocks should only be present when commits
  are performed while an MQGET is in-progress. However, it looks
  as though IVSA.lGetCursCnt is set to 1 although there are
  actually no in-progress MQGETs.
  .
   From the dump the change team can see that a very large
  proportion of these ITRQP control blocks have been incorrectly
  built. That is, the RPR of the message that they relate to
  should be in ITRQP_CRPR but the control blocks actually contain
  an address (also ITRQP_CSTCK should contain the STCK of the
  message, but it is 0). the Change team can see that this problem
  with the control blocks being incorrectly built could occur if
  there is a problem during MQPUT processing, for instance if the
  application passed an invalid buffer address, resulting in MQRC
  2004, MQRC_BUFFER_ERROR, which is the reason for the
  incorrectly-built ITRQP control blocks.
  .
   The change team has not been able to determine why these
  control blocks have not been released though (which lead to the
  short-on-storage experienced by the QMGR). We are taking this
  APAR so that the change team can investigate further how these
  incorrect ITRQP control blocks can go unreleased.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
  *                 Release 1 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Build up of invalid ITRQP control       *
  *                      blocks occurs following failing MQPUT   *
  *                      calls, leading to increased get/browse  *
  *                      times and storage shortages in the      *
  *                      queue manager address space.            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  An application attempting to put a message to a queue fails (for
  example, due to CSQI_PAGESET_FULL) and rel_locks is called to
  release any request locks obtained during the failing MQPUT.
  If the queue being put to is also being processed by any MQGET
  calls, an ITRQP is incorrectly queued to the IVSA for the
  queue by rel_locks.
  The invalid ITRQP causes any in progress MQGETs to restart
  scanning the page chain, delaying completion of the MQGET
  request.
  The invalid ITRQPs will be freed when the last MQGET using them
  completes. In some cases the page chain rescans caused by the
  invalid ITRQPs can delay the MQGET request long enough for
  further invalid ITRQPs to be created, resulting in additional
  rescans, and delays the freeing of the invalid blocks. This
  can lead to the storage used by the ITRQP pool growing and
  potentially leading to a short on storage condition and
  abends relating to insufficient available storages e.g. S878
  

Problem conclusion

• CSQIMPU2 is changed to no longer queue an invalid ITRQP to the
  IVSA chain following a failing MQPUT.
  100Y
  CSQIMPU2
  

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:

  UI19014

Modules/Macros

• CSQIMPU2
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R100 PSY UI19014

     UP14/07/22 P F407 ¢

Fix is available

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