How to forcefully free resources from JCL

vatish · New User Joined: 23 Jun 2007 Posts: 6 Location: Pune

Hi,

Can you guys please let me know if I there is some command which can forcefully release a dataset from one JCL and make it available for some other?

If this is not possible then can I code a step which releases all resources held by a Step once that step is complete?

Thanks,
Vatish

Aaru · Posted: Thu Sep 11, 2008 12:18 pm

Vatish,

expat · Posted: Thu Sep 11, 2008 12:22 pm

I would assume a dataset contention issue where one job updates a dataset and another then wwants to read it.

Split the job at end of update and then run parallel read jobs.

Escapa · Posted: Thu Sep 11, 2008 12:24 pm

expat · Posted: Thu Sep 11, 2008 12:27 pm

Would you care to explain the problem that you are experiencing, and perhaps us poor non psycics need not guess at your problem

dick scherrer · Posted: Thu Sep 11, 2008 7:39 pm

Hello,

As you've not posted your specifics, here's a generic consideration. . .

Why should "something" be able to free resources of an already running job? What whould happen to the partially complete work in the job that was rudely interrupted? Who gets to deal with that restart/recovery (yup, sequential files need integrity too).

What you have is a scheduling problem and i'd suggest you address it as such. There should be no consideration of forcefully "freeing" allocated resources while the job is running.

In some rare case, it may be necessary to cancel a production job so that some other can be run, but this should be very rare and is quite different than jerking the resource(s) away from the job on the fly.

As i mentioned, this is a scheduling problem and if you work with the scheduling people, it should not be too difficult to implement a satisfactory solution.

vatish · New User Joined: 23 Jun 2007 Posts: 6 Location: Pune

A step is writing to a data set and in the next step another program is reading this data set.

Actually it's a GDG and most of the time this is working fine but occasionally am getting abend with message "DATA SET RESERVATION UNSUCCESSFUL"

I believe this is contention error.

I could not find any other job which is accessing this GDG.

gcicchet · Posted: Fri Sep 12, 2008 11:02 am

Hi,

i think you will find its DFHSM.

Gerry

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

H Vatish,

I'm assuming that you're asking if the job that has control of the DS can release that control.

Have you tried FREE=CLOSE? This dos just what you would think - frees the DS upon CLOSE of that DS.

There are some caveats - look in the JCL Ref Manual for details.

dick scherrer · Posted: Sat Sep 13, 2008 1:36 am

Hello,

I recommend you work with your storage management or system support people to identify exactly what is causing this.

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

I keyed on the OP's 1st post that seemed to indicate 2 jobs were involved.

dick scherrer · Posted: Sun Sep 14, 2008 12:23 am

Hi Jack,

jaspal · New User Joined: 22 May 2007 Posts: 68 Location: mumbai

Hi Vatish,

Yuu can try with control card in both the jobs that they should not run parallel , if one job is executing other should go on hold it usually solves contention problem , either you can apply exclusive parm through scheduling.

Ex- control card.

Consider Job- A is having control card as

/*CNTL NNTRLCRD,EXC

And Job- B is having control card as

/*CNTL NNTRLCRD,SHR

then only one job will execute other will go on hold.
if A is executing B will go on hold and vice-versa.

Regards,
Jaspal
+919833814470

dick scherrer · Posted: Mon Sep 15, 2008 11:56 am

Hello,

Please note that the situation does not involve 2 jobs - the problem happens within a single job.

Maybe Vatish will post the cause of the contention when it is identified.

rahulbank · Posted: Sun Oct 26, 2008 11:24 am

Dear Vatish,

If you face this error again at that time try in log /D GRS,RES=(SYSDSN,DSNNAME)..this will tell you on who is holding it...