Using Max Usage Limit to change the availability of a resource

To change the global availability of a special resource after a specific number of operations have used it, independently of their successful completeness or actual run, use the Max Usage Limit option. For Max Usage Limit to be effective:
  • Set the Max Usage Limit for the special resource to a value different from 0
  • Set the Max Usage Type for the special resource to a meaningful value

When you set the Max Usage Limit, an internal usage counter is increased each time an operation allocates the resource. When the internal counter reaches the maximum usage limit, the global availability of the resource is reset to the value specified in the Max Usage Type field.

The usage counter is increased at each operation start and the resource availability is immediately reset if the maximum limit is reached. This means that the maximum usage limit is reached even if the operation fails or it is not submitted by the tracker, and the global availability of the resource is reset as soon as the operation is started.

For this reason, there are some cases where this option is not recommended. Consider, for example, that you are using WLM scheduling environment integration and your WLM job uses the special resource FILEX, whose maximum usage limit is 2 and maximum usage type is No. Suppose also that FILEX was already used once by another operation. When your WLM job is started and sent to the tracker, FILEX is allocated and the usage counter is increased to 2, reaching the maximum limit set. As a consequence, the FILEX global availability is immediately reset to No, preventing any operation from using it. If the scheduling environment is not available, the WLM job is set back to Ready, waiting for scheduling environment availability and the special resource is deallocated. Nevertheless, its global availability remains unchanged (not available), therefore the WLM job will not be able to start when the scheduling environment becomes available.

You can monitor the usage counter in the BROWSING A SPECIAL RESOURCE panel, but you cannot change the value calculated.

The Max Usage Limit value is valid only if the special resource is used for controlling purposes (the field Used For is set either to C or B).

For dynamically added special resources, the default values are:
Max Usage Limit
0, meaning that the function is not active
Max Usage Type
Reset
If you change the maximum usage limit so that the new value is incongruent with the current usage counter, the following actions are taken:
  • If the new maximum usage limit is 0 and the usage counter is nonzero, the usage counter is reset to 0. A message is issued in EQQMLOG.
  • If the new maximum usage limit is nonzero, but is lower than the usage counter, the usage counter is reset to 0 and the resource availability is reset according to the Max Usage Type. A message is issued in EQQMLOG.

The same actions are taken any time the daily plan batches make an update that causes incongruence with the current usage counter. Note that daily plan batch actions might be changed by the reapplying of the events generated during daily plan batch run. For details about current plan turnover, see the Diagnosis Guide and Reference.

You can check if the global availability of a special resource was changed due to maximum usage limit reached, in the Last Updated section of the BROWSING A SPECIAL RESOURCE and MODIFYING A SPECIAL RESOURCE panels.

Daily plan batch processes update the Max Usage Limit and Max Usage Type in the current plan extension (CX) data set with the first values available, taken in this order:
  1. The Max Usage Limit and Max Usage Type specified in the RD database, if the special resource is defined in the RD database.
  2. The Max Usage Limit and Max Usage Type specified in the old CX data set, if the special resource exists in CX.
  3. Max Usage Limit=0 and Max Usage Type=Reset, if the special resource is dynamically added.