Example of Detecting Catalog Resource Contention

In this example, the SYSZTIOT resource is used with the default wait time (10 minutes) and action (notification only). The information in this example also applies to the other resources to which resource contention monitoring applies (ALLOCLCK, SYSIGGV2, and SYSZVVDS).

If you receive system message IEC393I notifying you that a task or tasks is waiting on the SYSZTIOT resource, you can use the information in the message to determine if any action is needed to resolve the wait. Note that receiving this message does not mean that an error or problem exists - you may not need to take any action at all. If you cancel any of the jobs listed, consider first taking a dump of the CAS by issuing:

F CATALOG,TAKEDUMP

To get more information about the waiting jobs, use the information in message IEC393I as follows:

To get job name information, issue one of the following commands:
- To gather additional information about the waiting task, issue the following command:
```
F CATALOG,LISTJ(jobname)
```
- To gather information about all currently executing service tasks, issue the following command:
```
F CATALOG,LIST
```
After getting task information, you can redrive the holder of the SYSZTIOT so that the waiting task may complete:
```
F CATALOG,END(taskid),REDRIVE
```
If this command doesn't resolve the contention, you can use the following command to terminate the waiting task:
```
F CATALOG,ABEND(taskid)
```
To list all the tasks currently holding SYSZTIOT, issue the following command:
```
D GRS,RES=(SYSZTIOT,*)
```
This is useful if the task with an exclusive hold on SYSZTIOT is not a CAS task.

Unless specified otherwise in the IGGCATxx parmlib member, the system, by default, lets a task wait for the SYSZTIOT task for 10 minutes before writing a SYMREC record to the logrec data set and issuing message IEC393I. You can specify a different wait time using the following command:

MODIFY CATALOG,CONTENTION(SYSZTIOT,wait_time)

See MODIFY CATALOG Command Syntax for wait_time limits.

If you specify a non-default SYSZTIOT wait time on the MODIFY command, you must respecify that value after each system IPL. A non-default value does, however, persist through restarts of the CAS task.

Unless specified otherwise in the IGGCATxx parmlib member, the only action the system takes by default is notify (writing a SYMREC record to the logrec data set and issuing message IEC393I). You can specify that the system also re-drive the task using the following command:

MODIFY CATALOG,CONTENTION(SYSZTIOT,,R)

See MODIFY CATALOG Command Syntax for action-flags , which can be used to specify re-drive.

If you specify a re-drive action for SYSZTIOT on the MODIFY command, you must respecify that value after each system IPL. A non-default action-flags value does, however, persist through restarts of the CAS task.

Additional information:

You can display the current SYSZTIOT wait time and action by using the MODIFY CATALOG,CONTENTION command without parameters (see MODIFY CATALOG Command Syntax).
For information about using SYMREC records, see Logrec Information in z/OS DFSMSdfp Diagnosis z/OS DFSMSdfp Diagnosis.
For information about system message IEC393I, see z/OS MVS System Messages, Vol 7 (IEB-IEE)
For information about the MODIFY CATALOG command, see MODIFY CATALOG Command Syntax.