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Is a file can be allocate more than once ?

 
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rainye

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Joined: 11 Jul 2006
Posts: 8

PostPosted: Tue Jul 11, 2006 8:21 pm    Post subject: Is a file can be allocate more than once ?
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I am confused about the allocate.

When I allocate a DSN to a file(DD name), I cannot allocate the other one to the same file(DD name) unless I free the file. That means a file can only be allocate once.

However, when I submit a JCL , the system will allocate the DSN to file(DD name) SYSIN , SYSPRINT and something like that. As there are lots of JCLs running at the same time, there should be several DSNs being allocated to the same DD name SYSIN.

So I wanna know, is a file can be allocate more than once?
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cpuhawg

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Joined: 14 Jun 2006
Posts: 331
Location: Jacksonville, FL

PostPosted: Tue Jul 11, 2006 8:37 pm    Post subject: Re: Is a file can be allocate more than once ?
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If you are allocating them as NEW (to be created) rather than SHR or OLD (if they currently exist), it would make sense that you would have an allocation problem. As long as you are allocating them using SHR, there should not be a problem.

IDATASET = 'HLQ.DATA.SET.NAME'

"ALLOC FI(DDNAME1) DA("||IDATASET||") SHR REUSE"

"ALLOC FI(DDNAME2) DA("||IDATASET||") SHR REUSE"
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rainye

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PostPosted: Wed Jul 12, 2006 7:31 pm    Post subject:
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I tried as follow :

Allocate file(AABBCC) dsn( 'HLQ.DATA1') NEW success
Allocate file(AABBCC) dsn( 'HLQ.DATA2') SHR success
Allocate file(AABBCC) dsn( 'HLQ.DATA3') SHR fail
Free dsn( 'HLQ.DATA1') fail
Free dsn( 'HLQ.DATA1')
success


Is that means only one dsn can be allocated to each file ?

If I neglect the NEW/SHR/MOD/OLD/SYSOUT option, what's the default value or
what make them different ?

In the JESYSMSG, it never metioned the way it allocates data sets.

IEF237I JES2 ALLOCATED TO SYSOUT
IGD103I SMS ALLOCATED TO DDNAME PASSFILE
IEF237I JES2 ALLOCATED TO REPORT1
IEF237I JES2 ALLOCATED TO SYSIN



I will try something later
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cpuhawg

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Location: Jacksonville, FL

PostPosted: Wed Jul 12, 2006 7:48 pm    Post subject: Re: Is a file can be allocate more than once ?
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You are correct. You cannot allocate several different dataset names to the same file (DD) name without freeing the file name after each ALLOC.

You should never neglect using the NEW/SHR/MOD/OLD options because that tells REXX whether the file currently exists or is being created for the 1st time.

On the command line, TSO HELP ALLOC will provide you will all the parameters associated with ALLOC, but their is no indication that NEW, SHR, MOD, or OLD is a "default" parameter which means you should always code something.
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rainye

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PostPosted: Wed Jul 12, 2006 7:51 pm    Post subject:
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Thanks very much !
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