IBM Support

PK48164: PERFORMANCE ENHANCEMENT: CACHE HTB (HANDLE TABLE BLOCKS).

A fix is available

Subscribe

You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • In CICS TS 3.2 the size of the handle table block increase
    beyond 2K which is beyond the limit of the quickcell getmain.
    This fix will implement an alternative caching mechanism to
    improve the performance of HTB handling.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All.                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION: Performance degradation due to HTBs     *
    *                      exceeding the 2K size limit for         *
    *                      quickcell GETMAINs.                     *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    In CICS TS 3.2 the size of the handle table block (HTB)
    increased beyond 2K, which is beyond the limit of the quickcell
    GETMAIN. Whenever a HTB was required a domain call to SMGF was
    issued for the GETMAIN. The pathlength for a full domain call
    getmain is significantly more than the quickcell GETMAIN. HTBs
    are required for program links which issue EXEC CICS HANDLE
    commands, therefore the cumulative effect of this can be
    significant. In performance testing an increase of up to 0.5%
    CPU was observed compared with previous releases.
    
    Additional keywords: performance program link HTB HANDLE PUSH
                         AID CONDITION degradation
    

Problem conclusion

  • This fix is to implement a caching mechanism for HTBs.
    When HTBs are released they are saved on a chain for the task.
    Where possible, HTBs are obtained from the task chain rather
    than an SMGF GETMAIN. For programs with multiple links which
    issue EXEC CICS HANDLE or EXEC CICS PUSH HANDLE commands, this
    will significantly reduce the cost of acquiring an HTB.
    
    The CICS Transaction Server for z/OS Version 3 Release 2
    Supplementary Data Areas manual, GC34-6864-00, has been
    altered on page 286 to add new field HTB_NEXT_FREE to the
    Handle Table Block (HTB). HTB_NEXT_FREE overlays the existing
    field HTB_PREV_TABLE, therefore the following has been added
    infront of HTB_PREV_TABLE at offset X'10':
    
    Offset  Type          Len   Name (Dim)          Description
     Hex
    (10)   ADDRESS        4     HTB_NEXT_FREE      -> next free htb
    
    The same manual has also been altered on page 774 to add
    new field PTA_FREE_HTB_CHAIN to the end of the PTA
    (PG Transaction Area) control block at offset X'50' as
    follows:
    
    Offset  Type          Len   Name (Dim)          Description
     Hex
    (50)    ADDRESS       4     PTA_FREE_HTB_CHAIN  -> htbs
    (54)    CHARACTER     0     *
    

Temporary fix

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

Comments

APAR Information

  • APAR number

    PK48164

  • Reported component name

    CICSTS V3 Z/OS

  • Reported component ID

    5655M1500

  • Reported release

    500

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2007-07-02

  • Closed date

    2007-08-20

  • Last modified date

    2007-09-04

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

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

    UK28329

Modules/Macros

  •    DESHMDC  DESHMP   DESPGDC  DESPGDUF DESPGHM
    DESPGXM  DFHHMDCC DFHHMDCD DFHPGDCC DFHPGDCD DFHPGDM  DFHPGDUF
    DFHPGHM  DFHPGXM
    

Publications Referenced
GC34686400    

Fix information

  • Fixed component name

    CICSTS V3 Z/OS

  • Fixed component ID

    5655M1500

Applicable component levels

  • R500 PSY UK28329

       UP07/08/24 P F708

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.

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSGMGV","label":"CICS Transaction Server"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"3.2","Edition":"","Line of Business":{"code":"LOB35","label":"Mainframe SW"}},{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SG19M","label":"APARs - z\/OS environment"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"3.2","Edition":"","Line of Business":{"code":"","label":""}}]

Document Information

Modified date:
04 September 2007