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Detecting Catalog Resource Contention z/OS DFSMS Managing Catalogs SC23-6853-00 |
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Unless resource contention monitoring has been disabled for a resource,
the system monitors the following resources for contention:
The system checks the catalog address space (CAS) for tasks waiting for the resource beyond the specified wait time (by default, 10 minutes). Once a task is identified as waiting beyond the specified wait time, the system writes a SYMREC record to the logrec data set and issues message IEC393I displaying information about the waiting task or tasks. If the task is still waiting after 5 more minutes, this message is repeated. This message will be repeated every 15 minutes thereafter, if nothing changes. If a new hung task is identified or an old hang is resolved, the notification is reset to the new state at the time of the next system check (within 30 seconds). In addition to notification, the system can also re-drive. When re-drive is active, the first time a service task with an active resource passes the contention threshold, the service task is abended and the request is resubmitted to catalog for processing. The abend is a 91A-13, which will produce a 246-rsn dump, unless suppressed, and a LOGREC with error code 246 is generated out of module IGG0CLA9 for the service task. When the service task is abended, all resources it currently holds are freed, and the contention caused due to this request is removed. The original request submitted to catalog is then again assigned
to a catalog service task for processing (which could be, but need
not be, the same task). The service task will process the request
as if it were newly submitted, which leads to three possible results:
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