How to Replace DD Name?

Permander Malik · New User Joined: 24 Oct 2009 Posts: 11 Location: Mumbai

Hi All,

Is there any way to override a specific DDNAME in PROC from a JCL?

P.M

expat · Posted: Mon Nov 02, 2009 2:36 pm

Yes, click the button marked "IBM Manuals" at the top of any page, and go read the JCL reference manual.

Permander Malik · New User Joined: 24 Oct 2009 Posts: 11 Location: Mumbai

Suppose my Proc is like:
//PROC

//STEP1 EXEC PGM=PGM1

//DD1 DD DSN=FILE1

If Want to override file1 with file2 then in my JCL I will write as:
//STEP1.DD1 DD DSN=FILE2

But suppose I want to override DD1 with DD2.

Then how we can override DD1 with DD2 from a JCL?

expat · Posted: Mon Nov 02, 2009 2:53 pm

What exactly are you on about .................

You want to remove DD1 and insert DD2 ? Why ?

Anuj Dhawan · Posted: Mon Nov 02, 2009 2:55 pm

That's not overriding, by definition. When you want to override "DD1" with "DD2" -- what difference would that make to the JCL execution unless you change the DSN associated with that DD? Do you change the program executed in 'that-step" to include "DD2"(I assume COBOL program), if so, you should permanently change the JCL to use DD2 instead of using overrides.

Permander Malik · New User Joined: 24 Oct 2009 Posts: 11 Location: Mumbai

This is Just for my knowledge. Is there any way?
I guess one way to replace DD1 with DD2 is
Make DD1 as dummy from JCL
Add DD2 in JCL

expat · Posted: Mon Nov 02, 2009 3:29 pm

Correct, but as the program will open the DD names assigned within, it will not open DD2 and expect DD1

Permander Malik · New User Joined: 24 Oct 2009 Posts: 11 Location: Mumbai

That's True.
Thank You

Ronald Burr · Posted: Mon Nov 02, 2009 6:32 pm

Actually, you MIGHT try specifying

//STEP1.DD1 DD DDNAME=DD2

then adding

//STEP1.DD2 DD DSN=yadayadayada,etc.

This, in essence, tells the OS that any reference to DD1 should be redirected to DD2

Note: I know that this redirection works in runjcl ( especially to concatenate SYSIN statements with other files ), but do not know for certain, that it will work for overriding a PROC.

expat · Posted: Mon Nov 02, 2009 6:47 pm

A nice way around it, one that I had completely forgotten about, but it will depend on where the DD ststements are in relation to each other. I knew that there was sone limitation to using this method so thought I'd test it out.

The example below will work as the 'Option' DD names follow the DD name affected

Ronald Burr · Posted: Mon Nov 02, 2009 7:00 pm

Correct, according to the JCL Reference Manual:

Place a DD statement containing a DDNAME parameter in a job step or in a cataloged or in-stream procedure. The referenced DD statement must be later in the same job step, must be in the calling job step, or must be in a cataloged or in-stream procedure called by the job step.