In your original post you stated that you used to execute this task from a batch job.
All you need to do is convert this batch job into a Started Task.
copy jcl to a proclib that is defined in the MSTJCL member
modify jcl to run as procedure
Here is where you may have problems. You stated you wanted the task to run before AOC. I am assuming AOC starts JES.
If this is the case you will not be able to use any JES services.
If you are able to do this then all you need to do is updatethe commndxx member with something that looks like 'S TASK,SUB=MSTR'