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PM52172: EXEC CICS START COMMANDS WHICH SPECIFY AND EXPLICIT TIME IN THE FUTURE START IMMEDIATELY, AFTER Z/OS SYSTEM CLOCK IS MOVED BACK.

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APAR status

  • Closed as program error.

Error description

  • Immediately following the setting backward by 1 hour of the
    z/OS system clock (in support of a change from Daylight Saving
    Time to Standard Time) EXEC CICS START commands that specify
    an explicit time (using the TIME parameter) that is less than
    1 hour into the future beyond EIBTIME, will start immediately.
    .
    Here is a trace entry that shows this happening:
    .
    START TRANSID('FIC2' AT X'800523E0') TIME(32500 AT X'298417D8')
    TASK-62996 TCB-QR /008F81A0 RET-80082436 TIME-04:24:10
    4-0000  0032410C 0111310F E3D9D5F1 0062996C
      0010  00000000 00000000 0000000E 06000000
    .
    The above trace entry shows pieces of an AP E160 trace entry
    that is produced when Trace Component EI is set to level 1-2.
    It shows an EXEC CICS START command.   Data Area 4 traces the
    EIB.  The 1st word of that, 0032410C, is EIBTIME. This EIBTIME
    is 03:24:10. The TIME-04:24:10 in the 2nd line shows that at
    least part of CICS considers the time to be 04:24:10.  And the
    TIME(32500) on the 1st line shows that the EXEC CICS START
    command is specifying a time of 03:25:00.
    .
    At time of this START command z/OS considered the local time
    to be 03:24:10 .  But parts of CICS, since no EXEC CICS or
    CEMT PERFORM RESET has been done following the setting backwards
    of the system clock, think the local time is 04:24:10.  So
    while the TIME parameter of 03:25:00 is in the future with
    respect to EIBTIME and, therefore, the application program, it
    is in the past with respect to part of CICS.  That is why the
    START is actioned immediately.
    .
    Prior to some recent CICS APARs, in this interval between a
    setting backwards by 1 hour of the system clock, and an EXEC
    CICS or CEMT PERFORM RESET, EIBTIME would not contain the
    changed z/OS local time.  Instead it would continue to be set
    by CICS as if the system clock change had not happened.  So
    in the example above prior to the recent CICS APARs, even though
    the changed z/OS local time is 03:24:10, the trace entry time
    would be 4:24:10 and EIBTIME would be 4:24:10 and therefore the
    TIME specified on the START would be 4:25:00.
    .
    CICS/TS 3.2 APAR PK48346 changed CICS so that EIBTIME is
    updated with the up-to-the-second correct z/OS local time
    following an EXEC CICS ASKTIME.
    .
    CICS/TS 3.2 APAR PM26742 and CICS/TS 4.1 APAR PM26726 changed
    CICS so that EIBTIME is updated with the up-to-the-second
    correct z/OS local time from the beginning of the task, without
    an EXEC CICS ASKTIME having to be issued.
    .
    Let's say that at local time 2AM, the z/OS system clock is
    changed backwards so that the new local time is 1AM.  Without
    PM26742 or PM26726 applied, at 1:59:59 (prior to the change)
    a new task's EIBTIME would be setup as 01:59:59.  And then
    2 seconds later (after the change and the new local time is
    01:00:01), a new task's EIBTIME would be setup as 02:00:01.
    .
    But with either of those APARs applied, at 1:59:59 (prior to the
    change) a new task's EIBTIME would be setup as 01:59:59.  And
    then 2 seconds later (after the change and the new local time
    is 01:00:01), a new task's EIBTIME would be setup as 01:00:01.
    

Local fix

  • Do CEMT PERFORM RESET as quickly as possible following the
    z/os sytem clock time change.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All.                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION: Tasks started by a START command where  *
    *                      the START TIME is in the future start   *
    *                      immediately.                            *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    In the reported problem, a daylight saving change ( clock back
    one hour ) was made to an MVS clock. However no PERFORM RESET
    was issued by a CICS task ( running on the same MVS ) to resync
    the MVS clock and the CICS clock held in CSA field CSATODP. The
    recommendation is this is done immediately. As a consequence,
    the CICS system became overloaded with work.
    
    A task obtained its initial time from EIBTIME. It then issued a
    START command to run itself again in one minutes time. EIBTIME
    is initialized by an MVS TIME macro within DFHAPIN and would
    have reflected the changed MVS time so the START command would
    have been for just under an hour in the past, ( rather than one
    minute ahead ). However, Interval Control ( DFHICP ) uses the
    CICS clock ( CSATODP ) and so did not reflect the change to the
    MVS time because no RESETTIME had been issued. As a consequence,
    the STARTED task started immediately and the process repeated
    itself. The task was a heavy user of statistics and caused a
    spike of work to SMF.
    

Problem conclusion

  • CICS task attach logic has been amended such that if a new
    AUTORESETTIME parameter of IMMEDIATE is coded then the CICS
    internal clock ( in CSATODP ) will get reset immediately when
    DFHAPIN detects a mismatch between the MVS and CSATODP times.
    
    The following documentation change will be made:
    
    The CICS Transaction Server for z/OS Version 3 Release 2 System
    Definition Guide (SC34-6813-04) will be updated, the
    description for AUTORESETTIME will have an additional option
    of IMMEDIATE added, as a consequence, it will now read as
    follows:
                                                                   .
    AUTORESETTIME
     The AUTORESETTIME parameter specifies the action CICS should
     take for automatic time changes.
     AUTORESETTIME= IMMEDIATE|NO|YES
                              --
       Valid values are as follows:
       IMMEDIATE
            CICS will issue a PERFORM RESET command to
            synchronize the CICS time-of-day with the system
            time-of-day if, at the next task attach, the CICS
            time-of-day differs from the system time-of-day.
    
       NO   CICS issues message DFHAP1500 to indicate that a CEMT
       --   PERFORM RESET command is required to synchronize the
            CICS time-of-day with the system time-of-day.
                                                                   .
       YES  CICS issues a PERFORM RESET command to synchronize
            the CICS time-of-day with the system time-of-day
            if, at the next local midnight, the CICS time-of-day
            differs from the system time-of-day by more than
            30 minutes; for example, setting clocks forward or
            back to adjust for summer and winter time.
                                                                   .
    
    
    The CICS Transaction Server for z/OS Version 3 Release 2, Data
    Areas manual (GC34-6863-04 ) will be updated, as follows:
    
    The CSA will have 2 new fields added to byte CSAICIND thus:
    
    .... 1... CSAICIMM      IMMEDIATE specified on AUTORESETTIME
    .... .1.. CSAICRIP      Reset in progress
    
    
    Dsect TCADY ( the System TCA ) will have a new field added to
    byte TCAAPFLG thus:
    
    .... 1... TCATSUSP      DFHAPIN suspend
    
    
    Dsect SIT ( System Initialization Table ) will have a new field
    added to byte SITMISC thus:
    
    ..1. .... SITICARI      AUTORESETTIME=IMMEDIATE
    TEMPORARY FIX:
    ,
    

Temporary fix

  • FIX AVAILABLE BY PTF ONLY
    

Comments

APAR Information

  • APAR number

    PM52172

  • 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

    2011-11-15

  • Closed date

    2012-04-27

  • Last modified date

    2012-09-18

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

    PM52109

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

    UK78322 PM73143

Modules/Macros

  •    DFHAPIN  DFHAPTIM DFHCSAD  DFHCSAPS DFHPASY
    DFHPASYA DFHPASYM DFHPASYT DFHSIA1  DFHSIT   DFHSIT$$ DFHSITPS
    DFHSIT6$ DFHTCA   DFHTCAPS
    

Publications Referenced
GC34686304SC34681304   

Fix information

  • Fixed component name

    CICSTS V3 Z/OS

  • Fixed component ID

    5655M1500

Applicable component levels

  • R500 PSY UK78322

       UP12/05/05 P F205

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:
18 September 2012