IBM SC34-7012-01 manual Offline utility program, DFHJUP

Operating a recovery process that is independent of time-stamps in the system log data ensures that CICS can restart successfully after an abnormal termination, even if the failure occurs shortly after local time has been put back.

Offline utility program, DFHJUP

Changing the local time forward has no effect on the processing of system log streams or general log streams by the CICS utility program, DFHJUP.

Changing local time backwards will not affect the operation of DFHJUP provided you specify the GMT option on the SUBSYS parameter of the log stream DD statement in the DFHJUP JCL.

However, if you use local time on the SUBSYS parameter to specify the partitioning of a log stream for processing by DFHJUP, you must take steps to ensure the chronological sequence of time-stamps when adjusting clocks backwards. You can do this by stopping CICS regions until the new local time passes the old time at which the change was made.

User- or vendor-written journal utilities and DFHJUP exit programs may also be sensitive to local time changes. These should be checked to ensure that there are no problems posed by backwards time changes.

Forward recovery utilities (but not CICS VSAM Recovery 2.3) may also be sensitive to the time sequence of forward recovery log data. If you are not using CICSVR 2.3, check that your forward recovery utility can handle discontinuities in logged records.

The only circumstances in which forward recovery is jeopardized, while using CICSVR 2.3, are when you:

vTake a backup during the hour following the (local) time change (for example, at 01.30 after setting the time back from 02.00 to 01.00)

vPerform forward recovery using that backup with log records that span the time change

vSpecify local time instead of GMT to CICSVR.

If you use a backup taken earlier than the new local time, or if you specify GMT, CICSVR handles forward recovery successfully.

Chapter 11. Defining system and general log streams 121