In <[EMAIL PROTECTED]>, on 07/08/2005
at 12:23 PM, Bill Fairchild <[EMAIL PROTECTED]> said:
>What I was thinking when I said VSAM underlies page data sets was
>that one uses IDCAMS to create a new page data set via DEFINE
>PAGESPACE, and that what you get after the define is finished is
>the same as a VSAM linear data set with a large number of empty 4K
>blocks. I regret implying that standard VSAM channel programs are
>used to access these 4K blocks. A page data set also looks like a
>QSAM/BSAM/BDAM/ESDS file, in that all blocks have the same key
>length (0) and data length (4K), but certainly the individual blocks
>are read/written by radically different techniques.
BSAM/QSAM files do not, in general, have blocks of identical size,
even for RECFM=FBS. By contrast, a VSAM component always has a
consistent block size and a consistent CI size; the last two are not,
in general, the same, nor need the sizes match between the data and
index components of a KSDS.
>Media Manager has become the access method used in all new strategic
> products, such as DB2, IMS fast path, et al. Media Manager
>accesses data sets that have been defined as VSAM objects but uses
>different kinds of channel programs to access them than does
>standard VSAM.
What about data sets that are CI-formatted but not defined via AMS,
e.g., VTOCIX, HFS, PDSE?
--
Shmuel (Seymour J.) Metz, SysProg and JOAT
ISO position; see <http://patriot.net/~shmuel/resume/brief.html>
We don't care. We don't have to care, we're Congress.
(S877: The Shut up and Eat Your spam act of 2003)
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