Yes, before the EXEC card.
Actually, there is no 'allocation' of a file by z/VSE during the JCL
processing. The file is only 'allocated' once it is opened and
'unalocated' once the program closes the file.
For instance, if you have a 5 hour program, that just needs to update a
'totals' VSAM file at the end of the 5 hours, as long as the program
does not open the file until it needs the file, any other program can
use, including updating, the file until that time.
So, basically, you 'own' the file only while you have it opened.
One ramification is that you can't create a file simply by having in the
jcl, like in z/OS. You have to open it to create it.
Tony Thigpen
Paul Gilmartin wrote on 3/30/20 11:05 AM:
On Mon, 30 Mar 2020 10:11:53 -0400, Tony Thigpen wrote:
Coming from the z/VSE world, some of the JCL stuff in z/OS just is 'weird'.
I understand that in z/VSE tne DD statementw precede the EXEC for
the step. Intuitive because allocation is done first.
1) In z/VSE, the conditional jcl statements are more logical, not
something akin to RPN.
2) Our SETPARMs are sequential. You can have multiple SETPARMs of the
same variable in the same step and intervening statements are processed
using the 'then value' of the SETPARM.
3) We can modify and even define SETPARM values via programs as a way to
pass information between steps.
Don't get me wrong, there are good things in both, but sometimes issues
with the underlying basics of each lead to strange 'higher level' items.
Working daily on z/VSE, z/VM and z/OS really get's confusing sometimes.
Even simple things like responding to a console message. z/VSE needs the
outstanding message number, followed by a space, then the response. Yet,
z/OS usually needs a comma where z/VSE had the space, but not always.
-- gil
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
