Sometimes we find it necessary either to inactivate an active exit routine or the other way around. In order to achieve this, we need to use the MVS command:
JOBNAME=jobname – The job(s) name(s) for which this exit routine is to get control. If some other job calls the exit, this exit routine does not get control. The default value is * which means all the jobs. The default for the MODIFY parameter is to leave the jobname unchanged.