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SYSOUT = DUMMY or commenting out unneeded displays ??

 
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Sachinincsc

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Joined: 01 Oct 2008
Posts: 11
Location: Philadelphia, USA

PostPosted: Mon Nov 03, 2008 12:44 pm    Post subject: SYSOUT = DUMMY or commenting out unneeded displays ??
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How Does SYSOUT = DUMMY helps in performance. Would it be same if i comment all the Displays in the code ??
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enrico-sorichetti

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Joined: 14 Mar 2007
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Location: italy

PostPosted: Mon Nov 03, 2008 1:20 pm    Post subject: Reply to: SYSOUT = DUMMY or commenting out unneeded display
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from a pure performance point of view
taking away things ( displays in this case ) is the most appropriate action

DUMMYfying an output saves a bit of time and dasd space from a pure
data management point of view
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dick scherrer

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Joined: 23 Nov 2006
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PostPosted: Mon Nov 03, 2008 2:27 pm    Post subject:
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Hello,

Quote:
How Does SYSOUT = DUMMY helps in performance.
Who says it does? The only thing dd dummy "saves" is physical i/o and spool/dasd space. All of the work required to get to the point of the i/o is still done.

So, if a process reads a few million rows of some database tables to create a 200 line summary report and the report is assigned to dd dummy, tyhe savings is practically non-existent.

Quote:
Would it be same if i comment all the Displays in the code
The resulting output would be the same, but the resources needed would not change enough to measure.

On the other hand, if you have a process that writes millions of records to a qsam file and also produces a summary report and for debugging purposes you need to create the summary report, assigning the output qsam file to dd dummy will save considerable resources.

Do you have something more specific in mind?
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Sachinincsc

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Joined: 01 Oct 2008
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PostPosted: Mon Nov 03, 2008 3:07 pm    Post subject:
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Thanks

I got my Answer and My collegues tooooooooo
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Marso

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Joined: 13 Mar 2006
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Location: Israel

PostPosted: Mon Nov 03, 2008 7:26 pm    Post subject:
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To suppress my debugging displays, I usualy use this feature:
Code:
       ENVIRONMENT DIVISION.       
       CONFIGURATION SECTION.         
       SOURCE-COMPUTER.              IBM-370 WITH DEBUGGING MODE.
Code:
      D        DISPLAY '=DBG=> CODE=' WS-CODE ' - PAGE=' WS-PAGE
      D             ' - DATE=' WS-DATE

At compile time:
  • When SOURCE-COMPUTER is WITH DEBUGGING MODE,
    the "D" in column 7 is considered as a space: the DISPLAY is part of the program and will be executed.
  • When the SOURCE-COMPUTER line is commented,
    the "D" in column 7 is considered as a comment, the DISPLAY will not be executed.
Only drawback (as far as I know): you have to recompile the program to hide/restore the "D" lines.
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Robert Sample

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Joined: 06 Jun 2008
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Location: East Dubuque, Illinois, USA

PostPosted: Mon Nov 03, 2008 7:38 pm    Post subject:
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I code this as
Code:
       SOURCE-COMPUTER.                IBM-370
      *                                WITH DEBUGGING MODE
                                                          .
so I just have to take the asterisk out of column 7 to change the program behavior. Note the period is on the third line, just past and underneath MODE.
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