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Specifying the Number of Online Tasks and External Request Units

The MAXIMUM TASKS and MAXIMUM ERUS parameters specify the maximum number of user tasks (online tasks) and external request units that can be active concurrently. The size of these parameters can affect the amount of time spent by DC/UCF in searching the queues for tasks that are waiting to be executed.

Considerations

The number of online tasks and external request units that should be specified is a site-specific determination and is dependent upon factors such as the number of tasks processed each hour in a particular environment. When setting the MAXIMUM TASKS and MAXIMUM ERUS parameters on the SYSTEM statement, the following statistics should be considered:

Resource

Size of resource

Total

TCE

248 bytes

248 bytes

STACKSIZE

320 words

1,280 bytes

DCE

40 bytes

40 bytes

ECB * 3

8 bytes

24 bytes

DPE * 20

16 bytes

320 bytes

RCE * 15

16 bytes

240 bytes

RLE * 25

8 bytes

200 bytes

Total increase per task

 

2,352 bytes

Note that a value larger than the default (420) should be specified for the STACKSIZE when using CA ADS. If the STACKSIZE is at 420 and two tasks exceed stacksize and go into abend storage at the same time, the system will abort with an abend code of 3995.

Parameter

Amount increased

ECB LIST

3

DPE COUNT

20

RCE COUNT

15

RLE COUNT

25