On 11/6/2010 12:17 PM, Paul Gilmartin wrote:
On Sat, 6 Nov 2010 14:27:26 -0400, J R wrote:
Good point. However, update-in-place really only *need* be done during the
user's session to record profile changes, etc.
Extending the member should only be necessary when the ACCOUNT command is
adding segments, in which case it shoul be opened for output and recreate the
entire member.
... which leaves unused space in the PDS. If you do this enough times
you run out. Then what do you do?
This is exactly how ISPF profiles work. They place PAD records (the actual
characters P-A-D) at the end of the member to leave room for expansion. They
update the member in place whenever possible. When not possible, they write a
new member with a new PAD area. Standard PDS processing applies. If the library
gets full, it allocates new extents. When no more extents exist, a compress is
necessary. In practice, with this design philosophy the compress is almost never
necessary.
--
Edward E Jaffe
Phoenix Software International, Inc
831 Parkview Drive North
El Segundo, CA 90245
310-338-0400 x318
[email protected]
http://www.phoenixsoftware.com/
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