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PI77845: ASRA S0C4 ABEND IN CPSM METHOD CTUS

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

  • An abend in a MAS is possible if, during or after a CMAS
    shutdown, a MAS attempts to access or update control blocks
    that the CMAS has already FREEMAINed. It may happen during a
    small timing window if the MAS is starting and trying to
    connect to the CMAS at the same time that the CMAS is shutting
    down, but it may also happen at other times.
    .
    In the MAS job log, you will see a method list similar to the
    following:
    .
    EYUXL0905E Methods=CTUS,CTBT,CTBP,CAMS,XMSM,NLRA,XLOP
    .
    In the dump, the PSW in the exception trace for the abend
    places us in method CTUS / EYU0CTUS and we are attempting to
    access a field in the CLCB. In the case for which this APAR was
    opened, that field was CLCB_SCHED_CLOCK, but since the CMAS
    shutdown has already freed the CLCB ( link conversation block )
    then this field is no longer valid.
    .
    If the storage location has been reused already, this may cause
    an abend, depending on the storage contents. If an abend does
    not immediately occur, the storage could become corrupt.
    
    
    
    .
    .
    Additional Symptom(s) Search Keyword(s): KIXREVSVR
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All CICSPlex SM V5R2M0 and V5R3M0 Users      *
    ****************************************************************
    * PROBLEM DESCRIPTION: When you bring up a MAS region during   *
    *                      the termination of CMAS region that the *
    *                      MAS region is connected to, you may     *
    *                      experience S0C4 abend in method CTUS.   *
    ****************************************************************
    * RECOMMENDATION: After applying the PTF that resolves this    *
    *                 APAR, all CMASes and MASes must be           *
    *                 restarted. Note that the restarts do not     *
    *                 need to occur at the same time.              *
    ****************************************************************
    For CMAS to MAS and CMAS to CMAS communications, method EYU0CTUS
    (CTUS - Communication Transport Services Update Statistics) is
    called by a number of methods to update the link statistics of
    either the send or receive session. CTUS relies on LCNVB (Link
    Conversation Block) that is passed by the callers to reference
    the statistics area.
    
    When the CMAS region is terminated, method EYU0CLET (COMM LPROT
    ESSS Initial Contact Transient) is driven to release the control
    blocks allocated for CMAS to MAS communications, including
    LCNVBs. Therefore, when a MAS region is started during the
    termination of CMAS region that the MAS region is connected to,
    the LCNVB that CTUS gets from the callers could have been
    released by CLET, and subsequently been overwritten by other
    methods.
    
    In that case, method CTUS uses invalid LCNVB to reference the
    statistics area, and S0C4 abend occurs if the data is
    non-accessible.
    

Problem conclusion

  • Method EYU0CTUS has been updated to check existence of the CMAS
    region before using LCNVB passed from the callers.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI77845

  • Reported component name

    CICS TS Z/OS V5

  • Reported component ID

    5655Y0400

  • Reported release

    90M

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-03-08

  • Closed date

    2017-04-21

  • Last modified date

    2017-05-01

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

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

    UI46632 UI46633

Modules/Macros

  • EYU0CTUS
    

Fix information

  • Fixed component name

    CICS TS Z/OS V5

  • Fixed component ID

    5655Y0400

Applicable component levels

  • R00M PSY UI46632

       UP17/04/24 P F704

  • R90M PSY UI46633

       UP17/04/24 P F704

Fix is available

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Document information

More support for: CICS Transaction Server

Software version: 5.2

Reference #: PI77845

Modified date: 01 May 2017