Chris, Yes, I am aware of that. This thread started from an exit we run that
detects this type of concatenation in a DFSORT SORTIN due to fallout
encountered years ago involving the use of symbolics to override dataset names
in the concatenation at runtime. The fallout that occurred was because it
took days for the affected app groups to determine that the concatenated
datasets after the DUMMY dataset were never included in the SORTOUT. I was not
at this job when it occurred, but we are a bank, some maybe the affect was that
someone's bank accounts were not accurate(I don’t know). Some here call it a
feature, some call it a shortcoming, regardless, it is the way the system
operates. The problem for us then was that the job ended RC(0), and it took a
long time to figure out that the input data was ignored. That’s why the exit
came to life.
I know that the same behavior exits using IEBGENER, and IDCAMS REPRO copying
and we don’t have exits for those, and no one has complained.
Why do we have the ICE EXIT? Politics.
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Blaicher, Christopher Y.
Sent: Tuesday, February 04, 2014 10:10 AM
To: [email protected]
Subject: Re: Dummy dataset
David,
The use of DD DUMMY in a concatenation ends the processing of input data. The
following is from the JCL Reference Manual:
Data sets concatenated to dummy data sets: The system treats data sets
concatenated to a DUMMY data set as dummy data sets in that I/O operations are
bypassed. However, the system performs disposition processing and allocates
devices and storage for any concatenated data sets.
So, in your example you only read the file once. Without the DD DUMMY it would
read the file twice.
Chris Blaicher
Principal Software Engineer, Software Development Syncsort Incorporated
50 Tice Boulevard, Woodcliff Lake, NJ 07677
P: 201-930-8260 | M: 512-627-3803
E: [email protected]
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Jousma, David
Sent: Tuesday, February 04, 2014 8:45 AM
To: [email protected]
Subject: Re: Dummy dataset
No, we have users sorting data with path names as input. Just ran a test. Single path
input, concatenated, all work fine, unless they add a DD DUMMY between them. As a side
note, DFSORT doesn’t do a good job with dynamic sortwk allocations with PATH input
because it cannot accurately determine the input filesize. I had opened a ticket with
IBM on this, and all I got was "this is the way it is". My only option was to
tell my developers to hardcode sorkwk datasets in their job.
//DFSORT EXEC PGM=SORT
//SORTIN DD PATHDISP=KEEP,
// PATHOPTS=ORDONLY,
// FILEDATA=TEXT,
// RECFM=VB,LRECL=255,BLKSIZE=25496,
// PATH='/etc/httpd1443.conf'
// DD DUMMY
// DD PATHDISP=KEEP,
// PATHOPTS=ORDONLY,
// FILEDATA=TEXT,
// RECFM=VB,LRECL=255,BLKSIZE=25496,
// PATH='/etc/httpd1443.conf'
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Paul Gilmartin
Sent: Tuesday, February 04, 2014 8:37 AM
To: [email protected]
Subject: Re: Dummy dataset
On Thu, 30 Jan 2014 20:18:05 +0000, Jousma, David wrote:
We have an exit for DFSORT that scans TIOT to see if someone concatenated a
DUMMY dataset as input. Here is what I believe to be the relevant snippet of
code:
...
* CHECK FOR DUMMY DD STATEMENT
* NOTE: COULD ALSO BE DD *
DDCHK CLC TIOEFSRT,=AL3(0) Q. REAL UCB ADDRESS ?
BE DDBAD A. NO, BAD DD
...
How does this behave for DD PATH=...? Is the UCB address nonzero for zFS
files? Are you unwittingly prohibiting use of zFS in the SORTIN concatenation?
That would be imprisoning your users in the twentieth century.
Prohibiting "DD *" is also unduly harsh.
A similar question applies to Shmuel's suggestion of DEVTYPE.
The definitive test should be for DSNAME='NULLFILE'.
-- gil
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