PM74848: TASKS CAN HANG IN DEFERRED FCIOWAITS AND FCXCSUSP BECAUSE A BROWSE AGAINST A CMT DATA TABLE HAS NOT ENDED.

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

  • Under certain circumstances, it is possible for a
    STARTBR against a CMT Data Table to result in a VSAM Point to
    the source dataset, and then subsequent READNEXT or READPREV
    are handled through the Data Table without going through
    VSAM.  When that happens, the VSAM Point causes position to
    be held on one of the buffers until ENDBR from the application.
    That can lead to more Exclusive Control locking, and the
    circumstances leading to VSAM APAR OA36624 are met so that
    that problem may happen also.
    

Local fix

  • Make the source dataset NSR
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All.                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION: A STARTBR against a CICS Maintained     *
    *                      Data Table can lead to tasks hanging    *
    *                      with deferred FCIOWAITs and FCXCSUSPs.  *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    During a start browse against a CMT Data Table, if DT services
    receives a DTP_NOT_VALID response it will instead issue a start
    browse against the base data set (VSAM POINT). The following
    READNEXT or READPREV requests may not get this DTP_NOT_VALID
    response and so will have no need to attempt the request against
    the base data set. When an update request, such as a delete is
    issued, it will issue a VSAM GET UPD and it may enter an
    FCXCSUSP suspend due to the previous VSAM POINT that the STARTBR
    issued.
    
    In the majority of cases, the update request would have led to
    an AFCG abend because the VSAM GET UPD would have returned with
    0814. However in the reported problem the update request also
    met the circumstances leading to VSAM APAR OA36624. This meant
    that the update request did not abend but suspended waiting for
    the control interval and other tasks built up behind it.
    
    The same situation could occur if a reset browse (RESETBR)
    request received a DTP_NOT_VALID response as well.
    
    Additional Keywords: abendAFCG AFCG
    

Problem conclusion

  • DFHFCDTS has been altered so that if a POINT is requested
    against the source as part of a STARTBR or RESETBR request then
    a corresponding ENDREQ will also be issued against the source.
    This will ensure that when browsing CICS Maintained
    Data Tables, VSAM resources are not held unnecessarily.
    This fix also prevents self-deadlock AFCG abends from occurring
    in certain circumstances.
    

Temporary fix

  • FIX AVAILABLE BY PTF ONLY
    

Comments

APAR Information

  • APAR number

    PM74848

  • Reported component name

    CICS TS Z/OS V4

  • Reported component ID

    5655S9700

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-10-11

  • Closed date

    2012-10-31

  • Last modified date

    2012-12-04

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

    PM72706

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

    UK83194 UK83195

Modules/Macros

  •    DFHFCDTS
    

Fix information

  • Fixed component name

    CICS TS Z/OS V4

  • Fixed component ID

    5655S9700

Applicable component levels

  • R600 PSY UK83194

       UP12/11/09 P F211

  • R700 PSY UK83195

       UP12/11/09 P F211

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:

CICS Transaction Server

Software version:

4.1

Reference #:

PM74848

Modified date:

2012-12-04

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