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IOF Problem Resolution
Problem C06
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Description The "DAY TIME" field on the Job List Menu is sometimes inaccurate.
Background The IOF Job List Menu displays information contained in the JES2 Job Queue Element (JQE) control block. The JQE is part of the JES2 checkpoint. No I/O is required to fetch and scan information from the checkpoint.

The JQE has no timestamp field. In order to get the actual time a job ran, the SPOOL resident Job Control Table (JCT) control block would have to be read for every job.

IOF fabricates a job timestamp for jobs on the output queue. All output jobs have one or more Job Output Element (JOE) control blocks. The JOE control block also resides in the JES2 checkpoint and is easy to fetch.

The JOE control block does have a timestamp of sorts. Field JOECRTME is the timestamp in CPU STCK units when the JOE was created.

The "DAY TIME" field on the Job List Menu lists the timestamp from JOE with the highest JOECRTME value. For most jobs this gives accurate information about when the job finished execution. There are some problems with this technique however.

1. The STCK value does not take time zone, including daylight savings time, into account. So when a jobs runs in one time zone and is displayed in a different time zone the "DAY TIME" field will seem to be incorrect. A specific example of this occurs twice a year when the clock is changed to implement daylight saving time changes. Jobs run before the clock change but displayed after the clock change will seem to have run at the adjusted time.

2. Long running jobs can spin output anytime during the execution of the job. As output prints, causing the JOE control block for the output to disappear, the apparent time of execution as displayed in the "DAY TIME" field can change.


Note Daylight savings time changes always cause the DAYTIME field on the Job List Menu to appear to be an hour off for all jobs run before the time change. The store clock value used to generate the DAYTIME field does not take GMT offset into account.


Solution To display an accurate timestamp for a job, the Job Control Table (JCT) must be read. The "EXTEND" command on the Job List Menu and the Output Group Display causes the JCT for each job on the menu to be read. The accurate timestamp for each job is displayed in the "RAN/RECEIVED" field.


Caution When the EXTEND command is used, the JCT for each displayed job must be read. Pressing the DOWN key (PF8) causes the JCT for the next screen of jobs to be read. However, if a SORT or EXCLUDE command is also entered with EXTEND in effect, then all the JCT control blocks for all jobs on the menu must be read. When large lists of jobs or groups is being displayed, this can cause a significant delay.
More Help Click here to EMAIL a problem report to IOF Technical Support for additional assistance.


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Triangle Systems, Inc. PO Box 12752, Research Triangle Park, NC 27709
(919) 544-0090

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