PH16323: MQ ABEND5C6 00C90D06

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Hursley finds this problem occurs when the non-persistent
  scavenger removes an empty page from the queue's page chain,
   and tells the deferred write processor to bypass writing any
   updates to the page to the pageset on the basis that the page
   can no longer be referred to by any putters or getters.
   Ordinarily this is true, however when using get by message
   token the record is located directly rather than via the page
   chain. If the buffer containing the deallocated spine page has
   been stolen, an unexpected reference to the page via the
   message token causes the old page contents to be read from the
   pageset, leading to the reported symptoms.
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 8       *
  *                 Release 0 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Unpredictable behaviour occurs when     *
  *                      MQGET is called to get a deleted        *
  *                      non-persistent message, matching on     *
  *                      MsgToken, if the page containing the    *
  *                      message is no longer part of the page   *
  *                      chain.                                  *
  *                      Symptoms can include:                   *
  *                        Abend 5C6-00C90D06 in CSQIMGE9        *
  *                        Abend 5C6-00C93100 in CSQIMGE1        *
  *                        MQGET returning a deleted message     *
  ****************************************************************
  After the last message on a page was deleted, the non-persistent
  page scavenger removed the page from the queue's page chain.
  As the page contents could no longer be located and referenced
  via the page chain, any updates to the page were not written to
  the page set.
  The buffer containing the page was stolen, due to stress on the
  buffer pool, and was then reread from the page set when an
  application attempted to locate and get the deleted message
  by MsgToken. As the contents had not been written out, an old
  copy of the page was read back in.
  While attempting to return the message, CSQIMGE9 detected the
  IRH9 record did not match the IRH8, and the abend occurred.
  

Problem conclusion

• The non-persistent page scavenger is changed to release
  deallocated pages without bypassing writing out the contents of
  the page.
  

Temporary fix

Comments

APAR Information

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

  PH16269

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

  UI65490

Modules/Macros

• CSQISCN3 CSQISCN4 CSQISCN5
  

Fix information

• Fixed component name

  IBM MQ Z/OS V8

• Fixed component ID

  5655W9700

Applicable component levels

• R000 PSY UI65490

     UP19/10/29 P F910 ¢

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.