Task thresholds

You can use task threshold events to monitor both system and transaction class definition (TRANCLASS) task load by specifying that an event is to be emitted when the active task count crosses a threshold value.

Task thresholds are expressed as a percentage of the maximum number of active tasks in the system or TRANCLASS. For performance reasons, they are predefined.

The possible threshold values you can select are 50%, 60%, 70%, 80%, 90%, and 100% of the MXT system initialization parameter or TRANCLASS MAXACTIVE value.
  • You can filter on a threshold to indicate how close the system is to MXT. You can define more than one event to indicate various degrees of health as the threshold gets closer to the limit you set for the MXT system initialization parameter.
  • You can filter on the TRANCLASS and a threshold to indicate how close the TRANCLASS is to its MAXACTIVE value. You can define more than one event to indicate various degrees of health as the number of attached tasks gets closer to the MAXACTIVE limit you set for the TRANCLASS resource.

To avoid large numbers of events being emitted, events are emitted only when the number of active tasks crosses a new threshold boundary. For example, events are emitted during transaction attach when the number of active tasks exceeds a threshold and the previous goes higher than event was when the next lowest threshold was crossed. Events are emitted during transaction detach when the number of active tasks falls below a threshold and previously goes lower than event was when the next highest threshold was crossed. Figure 1 shows such examples.

Figure 1. Event emission opportunities
An example line graph of the values of MAXTASKS over elapsed time. Points on the graph indicate where the value of MAXTASKS crosses a threshold boundary and creates an event emission opportunity.

 1  No events are emitted when the number of active tasks exceeds the 50% threshold. Events are emitted during transaction attach only when the number of active tasks crosses one of the 60%, 70%, 80%, 90%, or 100% thresholds. No events are emitted when the number of active tasks falls below the 50% threshold, because the number of active tasks has not been above the 60% threshold since the last goes below 50% event.

 2  An event is emitted because the number of active tasks exceeds the 60% threshold for the first time since the previous goes above 50% event.

 3  An event is emitted because the number of active tasks exceeds the 70% threshold for the first time since the previous goes above 60% event.

 4  No events are emitted when the number of active tasks oscillates around the 70% threshold because the number of active tasks does not cross a threshold boundary to either exceed the 80% threshold or drop below the 60% threshold.

 5  An event is emitted because the number of active tasks drops below the 60% threshold for the first time since the previous goes below 70% event.

 6  A series of events are emitted when the number of active tasks progressively exceeds the 60%, 70%, 80%, 90%, and 100% thresholds.

Considerations

Event emission is not enabled for a TRANCLASS when its MAXACTIVE value is set to less than 10.

TRANCLASS threshold events are not emitted for those transactions defined as not having a TRANCLASS, that is, those defined with TRANCLASS(DFHTCL00).

If you require an event to be emitted when the system or TRANCLASS crosses the 100% threshold, and you need that event emitted as quickly as possible, consider the dispatch characteristics of the EP adapter.
  • For the system 100% threshold, ensure that the EP adapter will be linked to. It is possible that an attached EP adapter task would be queued until the MAXTASK condition is cleared.
  • For the TRANCLASS 100% threshold, ensure that the TRANCLASS that causes the event is not used for the EP adapter.