Using GDG to store Endevor CAP job C1MSGS1

Products

• Endevor

Issue/Introduction

The Endevor CAP option has been activated to speed up the processing of batch jobs and packages.

The sysout C1MSGS1 created by the Action request regions STC is stored into GDG-dataset, but when running CAP job, all submitted STC are frozen waiting exclusive access on the GDG base.

So how do we allocate the GDG-dataset in the CAP-procedure to avoid this contention issues?

Environment

z/OS
Endevor

Cause

The GDG absolute generation ( G000nV00) is always resolved at STEP initiation, using the Current Catalog  information at the time the step starts. 
This will allow the relative number (+0, -1 -n) to be resolved to the right entries.
In general updates to the GDG base must be serialized as you can't have multiple jobs updating it concurrently.
Since a +1 reference is specified with DISP=NEW, the ENQ is reserved on the base.

Resolution

In order to write the C1MSGS1 into a new Generation of GDG without issue, allocate the new generation GDG(+1) in the Main job instead of allocating it in CAP servers.
That main C1MSGS1 sysout combines output from all CAP server C1MSGS1 in a single output file and additional advantage is that it preserve the chronology of actions.