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Initaiize group variable

 
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misi01
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PostPosted: Mon Sep 27, 2021 7:51 am    Post subject: Initaiize group variable Reply with quote

I've seen the following code all over the place:-
Code:

move space to copybook
initialize copybook

In my mind, this is tautology and totally unnecessary. Surely, the second line should be enough ?
Or is there some quirk I'm missing. (And before anyone says that the first line ensures that FILLER fields are set to space, if they're filler fields, then logically they're not used)
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kolusu
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PostPosted: Mon Sep 27, 2021 8:05 pm    Post subject: Re: Initaiize group variable Reply with quote

misi01 wrote:

In my mind, this is tautology and totally unnecessary. Surely, the second line should be enough ?
Or is there some quirk I'm missing. (And before anyone says that the first line ensures that FILLER fields are set to space, if they're filler fields, then logically they're not used)


misi01,

INITIALIZE is a convenient, however it is a costly instruction as the compiler generates at least 3 instructions. So if you have large copybooks, then having a INITIALIZE statement in a loop can hurt performance. you can use INITIALIZE statements but narrow it down to ONLY numeric items. This may help reducing any S0C7 abends down the lane for any computations involving the numeric items.
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Terry_Heinze
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PostPosted: Tue Sep 28, 2021 10:00 am    Post subject: Reply with quote

One option would be to INITIALIZE the copybook one time, save it off, and every time thereafter, move the saved off initialized copybook to copybook.
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haatvedt
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PostPosted: Tue Sep 28, 2021 12:21 pm    Post subject: Reply with quote

One thing to consider is that the Initialize verb does NOTHING to FILLER areas and as such they would have garbage in them without the preceeding MOVE SPACES
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Terry_Heinze
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PostPosted: Wed Sep 29, 2021 8:43 am    Post subject: Reply with quote

Good point. Be sure to read all about INITIALIZE in the manual. It does/does not do what you might expect.
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Spolacek
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PostPosted: Wed Oct 06, 2021 11:28 am    Post subject: Reply with quote

If you're using COBOL version 6, there's an extension to the INITIALIZE verb that will also initialize FILLER fields.

Here's how the COBOL Language Reference describes it:

Code:
FILLER phrase

When the FILLER phrase is specified, the receiving elementary data items that have an explicit or implicit FILLER clause will be initialized.


https://www.ibm.com/docs/en/cobol-zos/6.3?topic=pdf-version-documentation

For example:

INITIALIZE MY-COPYBOOK FILLER.
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misi01
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PostPosted: Mon Oct 11, 2021 7:51 am    Post subject: Reply with quote

Thanks for the FILLER comment.
Talking about performance, my 2 cents' worth would also be for large tables. I always initialize the first line in the table, then I loop round moving row 1 to rows 2-n. Much faster and cheaper.
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