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lal · Beginner Joined: 21 Oct 2003 Posts: 70 Topics: 25

Hi Friends,
I have a following JCL in which the dataset though it is old and going to deleted is defined with SPACE=(TRK,0). Could anybody tell me what is the significance of the space parameter here ?

//STEP1 EXEC PGM=IEFBR14
//DD1 DD DSN=A.B.C,
// DISP=(MOD,DELETE,DELETE),
// UNIT=SYSDA,
// SPACE=(TRK,0)

Thanx in advance..

kolusu · Posted: Wed Dec 24, 2003 7:12 am Post subject:

lal,

Take a close look at the DISP parameter. It is defined as (MOD,DELETE,DELETE) . The disp = mod tries to append to the dataset if already exists or it will try to create the dataset. In the event of creating the dataset the space parameter is required.Since this step is intented to delete the dataset they haven't allocated bigger space parameters.

Hope this helps...

cheers

kolusu
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Dibakar · Posted: Thu Dec 25, 2003 11:27 pm Post subject:

I have a question - Is (new,delete,delete) is same as allocating a temporary dataset, I mean from efficiency point.

Diba.

kolusu · Posted: Fri Dec 26, 2003 12:56 pm Post subject:

Dibakar,

A temporary dataset is usually created to pass on the data to next step. The disposition is (new,pass,delete).

Disp=(new,delete,delete) is the default disposition if the disp parm is not specified. It is used for sortwork datasets where the sort program will use these temp datasets to sort the input data.Upon sorting these temp datasets are useless.On contrary we can allocate temporary datasets to pass info to the next step.

You really cannot compare these definitions from efficiency stand point.

Hope this helps...

cheers

kolusu
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lal · Beginner Joined: 21 Oct 2003 Posts: 70 Topics: 25

Hi Kolusu,
Thanx for ur answer. Well I wanted to know what do u mean by
SPACE=(TRK,0)...does it mean no space or some amount of space???

Dibakar · Posted: Thu Jan 01, 2004 11:15 pm Post subject:

Hi Kolusu,

I think temporary datasets don't go thru i/o process and was wondering if same is true for (new,delete,delete).

Thanks,
Diba

slade · Posted: Fri Jan 02, 2004 1:38 am Post subject:

Hi Diba,

What do you mean by "i/o process"?

Regards, Jack.

kolusu · Posted: Sun Jan 04, 2004 12:00 pm Post subject:

lal,

The parameter space is just used to allocate zero space and to avoid the job from failing with a JCL error.

Kolusu
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www.linkedin.com/in/kolusu

Dibakar · Posted: Mon Jan 05, 2004 6:28 am Post subject:

Okay, I was getting confused with temporary datasets on unit=VIO. Sometime ago I read, in this forum, that accessing records on a temp dataset on UNIT=VIO is faster because ... because ... because, well it had something to do with i/o (or not doing i/o).

I don't know what it was but I understood that in such cases the records are as readily available as a variable in a program is.

Diba.