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#1: Level number -77 Author: cobcurious,

Posted: Thu Jul 08, 2004 3:22 am
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Hi,
Can any body please tell that why we have level number 77 when 01 level can serve the same purpose as level number 77 ?
Are there any specific reasons we use level no 77 ?
Thanks and Regards
Cobcurious

#2: Author: kolusu, Location: San Jose

Posted: Thu Jul 08, 2004 5:20 am
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Cobcurious,

Check this link for a detailed description of special-level numbers

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IGY3LR10/5.1.6.3?SHELF=&DT=20020920180651&CASE=

Check this link for a detailed description of level numbers

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IGY3LR10/5.3.4?DT=20020920180651

Hope this helps...

Cheers

Kolusu

#3: Author: gkreth,

Posted: Thu Jul 08, 2004 9:59 am
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Our shop discourages (disallows, even, except for some old grandfathered code) the use of 77 levels, We are supposed to use Level 01s instead. Level 77 is apparently an "older" to describe independent elementary items in the Working-Storage or Linkage Sections. I think at one time Level 01 could only be used for group items.

Also, level 77 items cannot be subdivided any further.

I think part of the "no 77" philosophy is that it's better to collect individual items into groups instead of declaring large numbers of indistinguishable 77 fields. I'm not saying I agree 100% with this - sometimes fields truly have no relationship to other fields. But it's no big deal to me either way.

At our shop we usually have a Level 01 WS-MISC-FIELDS group and put our unrelated fields there.

HTH,

--Greg

--Greg

#4: Author: slade, Location: Edison, NJ USA

Posted: Fri Jul 09, 2004 9:03 am
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As I recall, 01 levels, in days of yore, took a "locator" register (I think that was the term - BLLs are one type), whereas 77 levels either didn't use them at all or many 77 data items could be grouped under one register. Apparently these registers were in short supply at that time.

As technology advanced this restriction was eased or eliminated and 77 levels lost their raison d'etre. They're tolerated today for their backward compatibility.

Has anyone else heard or remember anything like this?

Regards, Jack.

#5: Author: cobcurious,

Posted: Wed Jul 14, 2004 7:06 am
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Hi all,
Thanks a lot for your replies.
Regards
Cobcurious

#6: Re: Level number -77 Author: neilxt,

Posted: Tue Sep 19, 2006 4:09 pm
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cobcurious wrote:

Hi,
Can any body please tell that why we have level number 77 when 01 level can serve the same purpose as level number 77 ?
Are there any specific reasons we use level no 77 ?
Thanks and Regards
Cobcurious

In addition to what's been stated above, 01 levels are always located on a full word boundary. 77 levels merely take the next (however many) bytes of storage.

That few bytes hardly matters any more and you might generate inefficiencies if many binary fields are not on a word boundary.

Personally I like the visual separation of having truly independent fields marked with a 77.

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