IBM Support

PH16323: MQ ABEND5C6 00C90D06

A fix is available


You can track all active APARs for this component.


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


APAR Information

  • APAR number


  • Reported component name

    IBM MQ Z/OS V8

  • Reported component ID


  • Reported release


  • Status


  • PE




  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date


  • Closed date


  • Last modified date


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


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




Fix information

  • Fixed component name

    IBM MQ Z/OS V8

  • Fixed component ID


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.

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.0","Edition":"","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
01 November 2019