I have a few minutes, so I thought I would make some more comments.
1) z/OS JCL statements are much more complex than z/VSE because they
have a lot more 'options'. But, to be honest, most programmers just use
a small sub-set of what they could use.
Take a simple "I want to use a VSAM file". Here is what is normally used:
z/OS:
//POLYUPD DD DSN=PROD.HKY.VSAM.HPP002P.F03,DISP=SHR
z/VSE:
// DLBL TEITEST,'TEI.TEST.VSAM',,VSAM,CAT=VSESPUC
There are two major differences here:
z/OS (mostly) requires a DISP=. VSE (mostly) does not. VSE determines
the correct setting at open time.
z/VSE (mostly) requires a CAT=. z/OS uses ICF catalogs and can figure it
out by itself. This can be good or it can be bad. In z/VSE, almost every
shop will have files with the same name located in different catalogs.
This goes back to testing. With z/VSE, each partition (equal to a z/OS
'initiator') can be set the same catalog name so that it points to a
different physical catalog.
I can see some of you thinking: "That would make security impossible."
No, it does not. z/VSE manages security based on not just file name, but
catalog name.
Personally, I think the advantage is to z/VSE when using VSAM files. Of
course, those of you that have never had the chance to test using
different catalogs may understand it's advantage.
(Both z/OS and z/VSE can specify buffer space, which is about the only
other option used on VSAM files, so that item is a wash.)
Next up will be non-VSAM files.
Tony Thigpen
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