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PK85091: CEMT INQUIRE IPCONN HANGS IN A LMQUEUE WAIT AFTER TCPIP IS CLOSED VIA A CEMT SET TCPIP CLOSED.

A fix is available

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APAR status

  • Closed as unreproducible.

Error description

  • Customer forces TCPIP down via a CEMT SET TCPIP CLOSED command.
    Then he issues a CEMT IN IPCONN which results in the CEMT task
    getting stuck in a LMQUEUE wait for shared ISCB lock. The
    problem is caused by the CIST task that hold the ISCB chain
    lock and a SHARED lock on the IPCONN. Because the IPCONN has
    been autoinstalled, CIST calls DFHISIC DISCARD_IPCONN. During
    that process an attempt to acquire an EXCLUSIVE LOCK result in
    the task being suspended because there is a SHARED LOCK
    already own by a task. The SHARED LOCK happen to be own by
    the same task, CIST. CIST will never get resumed now.
    When the CEMT I IPCONN is issued it need a SHARED lock of the
    ISCB chain which has an EXCLUSIVE lock own by CIST. The task
    is now hung.
    .
    Additional Keyword(s) and Symptom(s):
    KIXREVSVR
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION: CEMT INQUIRE IPCONN hangs after issuing *
    *                      CEMT SET TCPIP CLOSED.                  *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    An IPCONN is autoinstalled when a new IPIC connection is
    established by a CICS Transaction Gateway ( CTG ) connecting
    to a TCPIPSERVICE defined with PROTOCOL(IPIC).
    Later on a CEMT SET TCPIP CLOSED command is issued. This causes
    a CIST task to be attached for every active IPIC TCPIPSERVICE
    definition.
    The CIST task loops through the IPCONN directory and attempts
    to terminate all IPCONNs associated with the selected
    TCPIPSERVICE. DFHISCO obtains a shared lock manager lock on the
    selected IPCONN then calls DFHISEM for FUNCTION PURGE_IPCONN.
    DFHISEM eventually calls DFHISIC for function DISCARD_IPCONN.
    DFHISIC has to obtain an exclusive lock on the IPCONN before
    discarding it. This request hangs as an exclusive lock cannot be
    obtained while a shared lock is still held.
    The CIST task will hang indefinitely with an outstanding
    request to obtain the exclusive lock.
    The same problem occurs if a CEMT SET TCPIPSERVICE IMMCLOSE
    command is issued against an IPIC TCPIPSERVICE.
    If a CEMT INQUIRE IPCONN command is now issued this will hang as
    it cannot obtain a shared lock on the IPCONN while there is an
    exclusive lock request still outstanding.
    
    ADDITIONAL KEYWORDS :- LMQUEUE
    

Problem conclusion

Temporary fix

  •             *********
                * HIPER *
                *********
    FIX AVAILABLE BY PTF ONLY
    

Comments

  • The PURGE_IPCONN logic in DFHISEM has been changed to ensure
    that the shared lock on the IPCONN is released before the
    IPCONN is discarded.
    DFHISCO has been changed to avoid releasing the IPCONN lock
    after calling DFHISEM for function PURGE_IPCONN.
    

APAR Information

  • APAR number

    PK85091

  • Reported component name

    CICSTS V3 Z/OS

  • Reported component ID

    5655M1500

  • Reported release

    500

  • Status

    CLOSED UR3

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2009-04-21

  • Closed date

    2009-07-06

  • Last modified date

    2009-08-03

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

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

    PK89455 UK48138

Modules/Macros

  •    DESISCO  DESISEM  DFHISCO  DFHISCOA DFHISCOM
    DFHISCOP DFHISCOT DFHISEM
    

Fix information

  • Fixed component name

    CICSTS V3 Z/OS

  • Fixed component ID

    5655M1500

Applicable component levels

  • R500 PSY UK48138

       UP09/07/11 P F907

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:
03 August 2009