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Rexx program Source

 
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cma rajith

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Joined: 28 May 2008
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PostPosted: Wed Jul 13, 2011 12:01 pm    Post subject: Rexx program Source
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Hello,

I have read that Rexx programs can be written in sequential datasets as well as PDS members.But PDS members are more preferred.Can anyone explain me the benefits of Rexx programs written in PDS over sequential files. Also I would like to know why it's recommended that PDS format should be VB and length should be 255. Is this is mandatory or a preferred parameter?

Thanks,
Ceema.
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Bill Woodger

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PostPosted: Wed Jul 13, 2011 12:06 pm    Post subject:
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Ease of use? Imagine you have 100 rexx programs in sequential datasets, all concatenated together vs one PDS with 100 members.

Try other than 255. I don't know why it is recommended, but don't believe that it has to be that.
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Garry Carroll

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PostPosted: Wed Jul 13, 2011 12:13 pm    Post subject:
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Also I would like to know why it's recommended that PDS format should be VB and length should be 255. Is this is mandatory or a preferred parameter?


This is not mandatory, it's site-specific. So in one site VB/255 is preferred whereas in another, FB/80 might be preferred.

Garry.
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Pedro

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PostPosted: Wed Jul 13, 2011 6:29 pm    Post subject: Reply to: Rexx program Source
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Imagine you have 100 rexx programs in sequential datasets, all concatenated together

I do not think a concatenation of sequential rexx programs would be of practical use. You have to execute sequential rexx programs through the use of the EXEC command.

re: ease of use. I think the main benefit is that you do not have to know entire name of the dataset. When you concatenate your PDS with SYSPROC or SYSEXEC, then to invoke a rexx program all you have to know is the member name. You can easily invoke with TSO %mymember command
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Bill Woodger

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PostPosted: Thu Jul 14, 2011 5:51 am    Post subject: Re: Reply to: Rexx program Source
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Pedro wrote:
Quote:
Imagine you have 100 rexx programs in sequential datasets, all concatenated together

I do not think a concatenation of sequential rexx programs would be of practical use. You have to execute sequential rexx programs through the use of the EXEC command.

[...]


I agree. Also, it just wouldn't work, as there is no "program name" for a rexx program (that I know of, anyway) other than the "unit name" within a "collective" (member of a PDS, file on a CMS disk, file in directory/folder).

I was just trying to emphasise how handy the PDS is, allowing multiple programs (members) within one dataset, and with access to multiple datasets, whose names you don't even need to know, with further members. By contrast, any approach with sequential datasets would be "unwieldy" at best, and even at best would not work.
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Pedro

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PostPosted: Thu Jul 14, 2011 6:10 am    Post subject: Reply to: Rexx program Source
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any approach with sequential datasets would be "unwieldy" at best, and even at best would not work.


Another aspect... if one of your sequential datasets calls another, it has to be done through the use of the TSO EXEC command. It is a maintenance nightmare if you have to change your high level qualifier.

But with PDS'es, one rexx program can call the other just by the member name. You can easily rename the PDS without having to edit the member to change within.
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Bill Woodger

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PostPosted: Thu Jul 14, 2011 6:24 am    Post subject:
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Emulating a call. Nice point, I didn't think of that. I hope no-one reads all this and comes up with a system written in rexx using sequential files, just because it can be done. Not very portable either.
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dick scherrer

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PostPosted: Thu Jul 14, 2011 9:32 am    Post subject:
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Hello,

Quote:
I have read that Rexx programs can be written in sequential datasets as well as PDS members.
And i believe any other thoughts about this should be set aside. This another of the zillion things that "can be done" but should not be done.

Even having such a discussion might lead some niave soul to implement - which will be no favor to anyone.
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cma rajith

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PostPosted: Thu Jul 14, 2011 9:49 am    Post subject:
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ThankYou all for your responses..

All are valid points, I understood why PDS is preferred over sequential files for rexx programs.

Ceema.
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