Going back to hazy memories...
GDGs needed the DSN specified, and the DCB info DCB=(dsn,....) so
that the allocation routines would correctly set the DSCB info
for the data set by getting the LRECL, RECFM, etc. so that
allocation would have all that. I'm not sure that DFP V3 fixed
this, or SMS or what. But I remember having to remember to do
these things back in the day, for SMF tapes and the like, when
doing the initial allocation for a GDG generation data set (GDS)
(+1, etc.).
Steve Thompson
On 1/7/2024 5:15 PM, Paul Gilmartin wrote:
On Sun, 7 Jan 2024 21:50:07 +0000, Gibney, Dave wrote:
DCB for the subparameters as been depreciated and, in my opinion, bad form for
most of the 40 years I worked on mainframes. The DCB=modeldscb form used for
new GDS allocations hasn't been needed since SMS came along. Early 90s'?
I may recall wrong, but I think LIKE was new with SMS.
Formerly needed; now deprecated. Why was it ever needed? I suspect the change
was less to accommodate SMS than UNIX files, which support attributes but no
DCB.
Answering my earlier question (IRTFM):
<https://www.ibm.com/docs/en/zos/3.1.0?topic=parameter-examples-like>
Example 2
//SMSDS7 DD DSNAME=MYDS7.PGM,LIKE=MYDSCAT.PGM,DISP=(NEW,KEEP),
// LRECL=1024
In the example, the data set attributes used for MYDS7.PGM are obtained
from
the cataloged model data set MYDSCAT.PGM. Also, the logical record length
of
1024 overrides the logical record length obtained from the model data set.
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