Paul Gilmartin wrote:
On Tue, 15 Jan 2008 15:01:58 -0700, Steve Comstock wrote:
And I might mention that DUMMY is __required__. We had some jobs that
ran with SYSIN being a DD *, but with no control cards. This is,
technically, equivalent to DUMMY, but not by ICEGENER. The same applies
to an "empty" dataset with no control cards. Just mentioning this
because it bit us once.
Well, that's not just for sorts and utilities;
A DD * with no lines is _not_ the same as DD DUMMY.
There are differences in allocation, for example.
Can you expand on this
I was just thinking that SYSIN type data gets
allocated out of the SPOOL, while DUMMY data sets
bypass allocation. Just ran a small test, since
I haven't really looked at this in years, and I
see on the JES2 job log:
IEF237I DMY ALLOCATED TO DD1
JES2 ALLOCATED TO DD2
JES2 ALLOCATED TO REPT
for this JCL:
//DD1 DD DUMMY,LRECL=100
//DD2 DD *
//REPT DD SYSOUT=*
also, for step termination:
SCOMSTO.SCOMSTO1.JOB02181.D0000101.? SYSIN
SCOMSTO.SCOMSTO1.JOB02181.D0000102.? SYSOUT
Of course, not much of a test. And Frank Y. and Bill
G. have provided some other insights.
> (or am I requesting too much a freebie)?
Ouch! Have I gotten too cheap again?
I've worked hard at being more upbeat,
more generous, and more humorous for
the last 6-9 months.
But (open message to designers): No! KISS dammit!
OPEN SYSIN; QSAM GET until you come to the end; then
CLOSE. Treat all empty data sets alike. Don't go poking
around UCBs and JFCBs and TIOTs and ... to make an
arbitrary distinction between an empty DUMMY data set, and
an empty instream data set, and an empty DASD data set,
and an empty allocated Unix path, and an empty tape data
set, and an empty (virtual) card reader data set, and an
empty terminal data set.
Treat them all alike; to do otherwise only adds an
unwarranted astonishment factor.
I'll grant some leeway that the error recovery for
a terminal data set is justifiably different from
that for a noninteractive data set.
-- gil
Kind regards,
-Steve Comstock
The Trainer's Friend, Inc.
303-393-8716
http://www.trainersfriend.com
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