PM77017: ACE AND EB CONTROL BLOCKS REMAIN ALLOCATED EVEN AFTER ASSOCIATED WORKER TASKS NO LONGER EXIST 12/11/15 PTF PECHANGE

A fix is available

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • ACE and EB control blocks remain allocated after the context
    associated with them have already ended. The orphaned control
    blocks are allocated from subpools of storage used by WebSphere
    MQ and so can still be freed if the QMGR is shutdown.
    

Local fix

  • Recycle queue manager
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
    *                 Release 0 Modification 1 and Release 1       *
    *                 Modification 0.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: After applying PTF UK79818 (for Version *
    *                      701) or UK81712 (for Version 710), a    *
    *                      leak of ACE/EB control blocks can occur *
    *                      when an application task using WMQ      *
    *                      private contexts ends without first     *
    *                      ending all the contexts.  This can      *
    *                      happen due to a normal end without      *
    *                      appropriate cleanup, or due to an       *
    *                      application abend.                      *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Various changes were made in PM64200 (for V701) and PM67446 (for
    V710), corresponding to the above PTFs, helping to ensure that
    RRS threads do not go through deferred end-of-task if
    end-context has taken place or deferred end-context has been
    scheduled (or vice versa).  This code added extra serialization
    using the CCBDENDS flag to ensure that ACE/EBs were not cleaned
    up by one process while queued for cleanup by another.
    
    Following APAR PM64200 and PM67446 a problem can be seen during
    an abend or a normal end (without ending the context) of an
    application that creates a private context.  In this case a
    private context is scheduled for deferred end-context
    processing, which sets CCBDENDS to ensure that no-one else tries
    to deal with it.  When RRS is called to end the context during
    processing of the deferred end-context, RRS drives CSQ3RRSX exit
    for CTX_END_CONTEXT_EXIT.  CSQ3RRSX finds that CCBDENDS is set
    on and does not free the ACE/EB for the context and the ACE/EB
    gets orphaned.
    

Problem conclusion

  • The code has been changed to reset CCBDENDS prior to calling RRS
    to end-context.
    010Y
    100Y
    CSQMCTXE
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM77017

  • Reported component name

    WMQ Z/OS V7

  • Reported component ID

    5655R3600

  • Reported release

    010

  • Status

    CLOSED PER

  • PE

    YesPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-13

  • Closed date

    2012-12-21

  • Last modified date

    2013-03-04

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

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

    UK90568 UK90569

Modules/Macros

  • CSQMCTXE
    

Fix information

  • Fixed component name

    WMQ Z/OS V7

  • Fixed component ID

    5655R3600

Applicable component levels

  • R010 PSY UK90568

       UP13/02/02 P F302

  • R100 PSY UK90569

       UP13/02/02 P F302

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.



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Document information


More support for:

z/OS family

Software version:

7.0.1

Reference #:

PM77017

Modified date:

2013-03-04

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