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PI34742: WMQ V7: CSQQSSON +X'38E' CAUSES AN OVERLAY OF AN IMS TCB, CAUSING ABENDS DURING VSM PROCESSING 15/02/11 PTF PECHANGE

A fix is available

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APAR status

  • Closed as program error.

Error description

  • After WebSphere MQ 7.1.0 PTF UI11931 for APAR PM90755 and z/OS
    Recovery Termination Management (RTM) APAR OA46028 are applied,
    an overlay can occur of the TCBMSS field for the IMS TCB for
    DFSPCC20.
    
    Because of the TCBMSS overlay, Virtual Storage Manager (VSM)
    control block VSWKDQE may end up with a non-zero value which
    does not point to a valid DQE. This results in an ABEND0C4 in
    IGVFSDQE JBB778H +x'1AA' because storage pointed to by Reg6 is
    not available. This module is involved in doing subpool
    freemains.
    
    The CSQQSSON code that caused the overlay is using Reg11
    without initializing it, and R11 is not an interface register
    between RTM and resource managers.  Prior to the code change
    introduced by APAR OA46028, Reg11 residually pointed to an STCB
    when CSQQSSON was invoked.  Therefore, the overlay was to
    STCB+18 which happens to be a reserved field and therefore did
    no harm.  However, after the OA46028 code change, Reg11
    happened to residually point to a TCB when CSQQSSON was
    invoked.  Therefore, the overlay was to TCB+18, the TCBMSS
    field, leading to downstream effects on VSM processing.
    
    This problem is only evident in the UI11931 version of CSQQSSON.
    
    
    Note that an overlay may still occur without the PTF for
    OA46028 applied. The exact symtpoms that this overlay may
    cause are unpredictable.
    
    Additional Symptom(s) Search Keyword(s):
    Follow-on symptoms in IMS may include:
    - ABENDB78 ABENDSB78 B78 SB78 S0B78 RC4 4 00000004 B78-04
      The freemain failed because R8 has been loaded from the
      TCBMSS field, which should be a Subpool Queue Element
      (SPQE)address.
    - ABEND378 ABENDS378 378 S378 S0378 RC14 14 00000014 378-14
    - IMS MPP region hangs or has high CPU after /STO REGION is
      issued.
      hang hung hanging performance
    - IPCS VSMDATA in a dump reports possible storage overlays:
      => FBQE Area Address is invalid - possible storage overlay
    
    ABEND0C4 ABENDS0C4 0C4 S0C4 S00C4  CSQQWait_Termination
    

Local fix

  • Back out MQ APAR PM90755 or RTM APAR OA46028
    -
    Also, a ++APAR is available from the MQ support team.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
    *                 Release 1 Modification 0.                    *
    ****************************************************************
    * PROBLEM DESCRIPTION: CSQQSSON overlays 4 bytes of system     *
    *                      storage when an IMS MPP terminates      *
    *                      following application of PM90755        *
    *                      (UI11931).                              *
    *                      Following application of OA46028        *
    *                      (UA75442/UA75443) this overlay          *
    *                      leads to abend0c4 errors in VSM         *
    *                      modules during IMS MPP termination      *
    *                      as described by OA47064.                *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    During termination of an IMS MPP that has connected to a queue
    manager, CSQQSSON's RESMGR routine is called.
    Following application of UI11931 this routine incorrectly
    overlays 4 bytes of storage at R11+x18. Prior to OA46028 the
    contents of R11 on entry to the resmgr routine meant that the
    overlaid storage was unused, and consequently no errors
    occurred.
    However, following application of OA46028 the contents of R11
    on entry to the resmgr routine have changed, and R11+x18
    contains the address of a VSM control block.
    The overlay prevents VSM routines locating this control block
    correctly, leading to abend 0C4 errors.
    

Problem conclusion

  • CSQQSSON is changed to prevent it overlaying storage using R11.
    100Y
    CSQQSSON
    CSQQTMID
    CSQQTTHD
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI34742

  • Reported component name

    WMQ Z/OS V7

  • Reported component ID

    5655R3600

  • Reported release

    100

  • Status

    CLOSED PER

  • PE

    YesPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2015-02-10

  • Closed date

    2015-03-03

  • Last modified date

    2015-05-06

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

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

    UI25577

Modules/Macros

  • CSQQSSON CSQQTMID CSQQTTHD
    

Fix information

  • Fixed component name

    WMQ Z/OS V7

  • Fixed component ID

    5655R3600

Applicable component levels

  • R100 PSY UI25577

       UP15/04/17 P F504 {

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

Modified date:
06 May 2015