COBOL MVS options

BiswajitDG · New User Joined: 06 Apr 2018 Posts: 3 Location: USA

We have a work in progress and as part of that we need to auto assign priority to access certain resource based on the class of the job that is running our cobol. Could not find class of the running job from the MVS control blocks. Is there any other way to do this or is this hidden somewhere in MVS blocks?

documentation.microfocus.com/help/index.jsp?topic=%2Fcom.microfocus.eclipse.infocenter.studee60ux%2FHCOMCMCBLKS005.html

Robert Sample · Posted: Fri Apr 06, 2018 1:49 am

Is your site JES2 or JES3? This would impact the control blocks you need to review.

Does your site use JES-managed initiators or WLM-managed initiators? If your site uses WLM-managed initiators, then you CANNOT auto assign priority -- WLM will run jobs based on their service class.

This is the type of question you REALLY need to be asking your site support group since we don't work at your site and have no idea how it is set up.

steve-myers · Posted: Fri Apr 06, 2018 8:37 am

As one level, Mr. Sample is correct, but he is simplifying the situation.

In MVS, there are three priorities

A JES related workload selection priority.
In MVS, an address space related selection priority that determines when an address space is selected for execution, relative to other address spaces.
In MVS, when multiple tasks are running within an address space, a priority that determines the order in which the task is selected.

Once a job starts executing, the first priority cannot be altered. It's too late, anyway. In any event MVS workload management has pretty much taken over this task.

The second priority is pretty much determined by MVS workload management. A user job cannot alter or influence the priority. I don't really know if a user job can even determine what it is. MVS workload management attempts to maximize system operation based on rules defined by the system programmers. Roughly 30 years ago, IBM decided

The system programmers were mostly incompetent to do this. I'm not sure I disagree.
System activity changes too quickly for human intervention to make much difference. A human must determine there is a problem, figure out what can be done to correct the problem, and (hopefully) correct the problem. Here I agree.

In response, IBM built the present workload manager.

The third priority can be influenced by the user program. The only time this matters is when when the program is operating subtasks. In 50 years I've only tried this once, and I never knew if it mattered. I ran several subtasks. Most of the time each subtask was I/O bound, but there were periods when it was CPU intensive. Just before a subtask went CPU bound I dropped its relative priority, and raised it when it went I/O bound again. Like I said, I never knew if it really helped.

BiswajitDG · New User Joined: 06 Apr 2018 Posts: 3 Location: USA

Understood. Thank you Steve and Bob. Will follow up with our site people.

Nic Clouston · Posted: Sat Apr 07, 2018 2:16 am

Rohit Umarjikar · Posted: Sat Apr 07, 2018 2:41 am

I have seen "Mr. Robert Sample "referred to as "Bob" in this week another post and in past as well. People have created their own alias.

enrico-sorichetti · Posted: Sat Apr 07, 2018 3:11 am

Robert Sample · Posted: Sat Apr 07, 2018 3:20 am

Yes, I correct people calling me "Bob" -- my name is Robert. My father's name was "Bob" but he is not I and I am not him.

BiswajitDG · New User Joined: 06 Apr 2018 Posts: 3 Location: USA

Robert - Apologies and will address you by your first name going forward.