Tom Marchant wrote:
On Thu, 17 Jul 2014 17:24:30 -0400, Thomas David Rivers wrote:
- After the OPEN has finished, the DCBBLKSI field remains 0.
Do you have a DCBE?
No DCBE - just an ol' below-the-line DCB.
- In this case, we _could_ use 32760 for the size of the read buffer
to allocate.. that seems rather large... and, does LBI mean that
the buffer should be larger?
From Using Data Sets in 3.2.3.1.1 Large Block Interface (LBI),
"Currently blocks of more than 32 760 bytes are supported only on tape, dummy data
sets, and BSAM UNIX files."
In any case, a block on a DASD can't be more than a track.
But - what's the tracklen of a "BSAM UNIX file?"
So, does this mean you can use 32760 if the DD is not allocated to a
PATH, TAPE
or DUMMY? What do you use if the DD is allocated to one of those? What
does one
use then?
That is - do we yet have an answer to the question of "how large an area
should
be allocated for a RECFM=U to ensure you have enough space for the first
READ?"
Or, is the question simply not answerable without looking at the VTOC
(or an SVC 99 query?)
I'm hoping I have a bug somewhere - but this same code works just fine
for F/FB/V/VB
files... I'm just really surprised that the DCBBLKSI isn't filled in
after the OPEN... in my
pouring thru the documentation, I could only find sentences that
indicate the DCBBLKSI
is only filled in by OPEN for F/FB/V/VB files. This leads me to
wonder, perhaps it
simply isn't filled in for RECFM=U? (Which is what appears to be happening.)
It just seems like, perhaps wallowing in naivite, that if you can fill
it in for the
other RECFMs, and it would be so darn convenient for this; that I can't
be the
first guy to stumble over it... and, if it weren't filled in, why not?
- Many Thanks -
- Dave Rivers -
--
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