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GDG version: SPACE parameter when DISP=OLD coded


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padma_prakasam

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Joined: 06 Oct 2005
Posts: 31

PostPosted: Fri Mar 30, 2007 9:48 am
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Hi,

In one my jobs i have created a GDG version with space CYL(150,5). I'm using the same version in another job with DISP=OLD. The DD statement is coded like this,

//FILEIN DD DSN=gdg.name,SPACE = (TRKS,(15,5)),DISP=OLD

This is being used as output file in that step. What for we give SPACE parameter when DISP=OLD coded? Does it override space?

Thanks,
Padma
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muthuvel

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Joined: 29 Nov 2005
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Location: Canada

PostPosted: Fri Mar 30, 2007 11:26 am
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Padma,
This is what the manual says,

Quote:
When you specify DISP=OLD for a PDS or a PDSE, and you also specify a member name in the DSNAME parameter, the data set must already exist. If the member name already exists and the data set is opened for output,the system replaces the existing member with the new member. If the member name does not already exist and the data set is opened for output, the system adds the member to the data set.


I think the above quote's will make you to understand.To be more clear,If the version of the GDG is not there it will create a new version with the given SPACE parameters when coded with DISP=OLD.
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raak

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PostPosted: Fri Mar 30, 2007 12:22 pm
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Hi Muthuvel,

When u code DISP=OLD and the version of GDG is not present, u should get a JCL error....

and the quotes that u gave is referring a PDS and It's member. not a PS..


And Padma,

The Space parameter coded for the same generation doesn't make any sense for me. I don't think the space parameter can be overridden for an existing dataset even if u use DISP=OLD.


Corrections are welcomeee icon_surprised.gif
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expat

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Joined: 14 Mar 2007
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PostPosted: Fri Mar 30, 2007 12:31 pm
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Quote:
//FILEIN DD DSN=gdg.name,SPACE = (TRKS,(15,5)),DISP=OLD

Nice standards you have - an output file allocated to FILEIN DD

I think that you can actually change the space allocation parameters when writing to a pre existing file, but it will only work for secondary allocations.

OK, why have you created the GDG in a different job when you are going to write to it in another job, what is the point of that. You are using up at least 150 cylinders of DASD resource until the job that writes to the GDG is processed.

Why not create the GDG version when it is written to, and then you can use the RLSE parameter to make sure that you do not hold and waste any unused DASD resource.

And if your storage group have got things set up correctly your GDG will have immediate free space release via DFSMSsms, and if it is empty will be just ONE cylinder in size.
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padma_prakasam

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PostPosted: Fri Mar 30, 2007 2:15 pm
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Thanks for your information. And the DD name actually coded was different. My intention was to clarify wiht the SPACE parameter. Just for an example i gave the name FILEIN.
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muthuvel

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PostPosted: Fri Mar 30, 2007 4:05 pm
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Raak,
Raak wrote:
Quote:
Hi Muthuvel,

When u code DISP=OLD and the version of GDG is not present, u should get a JCL error....

and the quotes that u gave is referring a PDS and It's member. not a PS..

Corrections are welcomeee


Yes ,you are right if i am mentioning the version not present or new version(+1) I should get a JCL error.

But Padma wrote
Quote:
I'm using the same version in another job with DISP=OLD.


So In this case it will not cause a problem

Please try out.I tried it and found working icon_wink.gif
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