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ANDY · Beginner Joined: 07 Feb 2004 Posts: 127 Topics: 67

What's difference UNIT=SYSDA AND UNIT=(SYSDA,3) ?

I think it is for enlarge dataset space. but as I know the parameter SPACE
is for allocate space. Why need this one for space?

Thanks

Andy

kolusu · Posted: Tue Jul 13, 2004 5:32 am Post subject:

Andy,

DD statement DDX requests 3
Unit=sysda will request just 1 device. where as unit=(sysda,3) requests that the system assign three direct access devices to the data set.

If you specify unit=(,3), it requests that the system assign three devices to the data set. The system obtains the device type from the catalog.

Btw this is clearly covered in the JCL reference manual which can be accessed via quick manual links

And here is that link

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IEA2B631/12.62.6?SHELF=&DT=20030423085347&CASE=

Hope this helps...

Cheers

Kolusu
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Kolusu
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slade · Posted: Wed Jul 14, 2004 12:17 pm Post subject:

Something to keep in mind when opting for multivol allocations:

The 2ndary space specified can potentially yield 3X the space if you use the same alloc as you used for a single volume.

It has its advantages and disadvantages, for example:

You can reduce the sec alloc thereby increasing you chances of getting the space in smaller increments.

If you don't reduce it, a runaway job will ececute longer before it abends w/an x37.

Regards, Jack.

This was pointed out to me by Kolusu a while back.

ANDY · Beginner Joined: 07 Feb 2004 Posts: 127 Topics: 67

Thanks

Andy
_________________
cheers,
Andy