On 11/11/23 21:03, Ed Jaffe wrote:
On 11/11/2023 6:40 PM, Paul Gilmartin wrote:
On Sun, 12 Nov 2023 02:16:07 +0000, Seymour J Metz wrote:
Solves what problem? Unix doesn't have records, so you have to
impose your own record structure and tell seek the byte offset.
He said FB. That makes the calc simple.
FB allows short blocks. FBS would be needed to do true skip-sequential.
But of course short blocks, other than the last block, will not be
present with RECFM=FB sequential datasets that are created by the usual
means with a single OPEN-CLOSE sequence -- internal short blocks only
happen when the dataset is created as multiple segments with subsequent
OPENs appending to existing records by opening the dataset with
DISP=MOD, as each CLOSE has the potential to create a short block. So
in those contexts where you know from the way the dataset was created
that the "allowed" embedded short blocks cannot actually be present,
RECFM=FB works also. If you wanted to verify whether a specific
FB-created dataset contained internal short blocks, i believe you could
run any utility that would read the entire dataset using JCL to override
the dataset RECFM with RECFM=FBS, and you should get some error
indication like IEB174I if internal short blocks are found.
JC Ewing
--
Joel C. Ewing
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
