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To Understand EXECIO Read Parameter OPEN


IBM Mainframe Forums -> CLIST & REXX
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Ilavenil

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Joined: 16 May 2018
Posts: 4
Location: India

PostPosted: Tue May 29, 2018 1:59 pm
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Hello All,

I wish to understand more about the EXECIO read parameter OPEN. The manual says that EXECIO will open the dataset and place the cursor based upon linenum parameter. I tried the following statements

Code:

"EXECIO 3 DISKR INDD (SKIP"
"EXECIO 1 DISKR INDD (FINIS"
"EXECIO 1 DISKR INDD 5 (FINIS"


I was expecting an error, but irrespective of not opening the file explicitly, the file has been opened by EXECIO and the data has been returned!

I can understand about FINIS as if we are not closing the file explicitly, it will affect the concurrent execs that are waiting for the dataset based upon the locks. But I could not figure out the practical significance of OPEN. can anybody advice?
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Nic Clouston

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Joined: 10 May 2007
Posts: 2455
Location: Hampshire, UK

PostPosted: Tue May 29, 2018 7:19 pm
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Quote:
The manual says that EXECIO will open the dataset and place the cursor

No it does not. The manual says
Quote:
if you also specify a non-zero value for the linenum operand, EXECIO sets the current record number to the record number indicated by the linenum operand.

No mention of a cursor.

You use OPEN to explicity open the data set - good programming practice - and set the current record number. This is the equivalent of SKIP on the FIRST (only) access to the data set.
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Willy Jensen

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Joined: 01 Sep 2015
Posts: 495
Location: Denmark

PostPosted: Tue May 29, 2018 9:38 pm
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EXECIO will do an implicit OPEN if the dataset is not already opened. So what you do is not an error.
You will get records 4 and 5 returned in the stack.
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