There is a third option you did not mention.  That is to deregister the ENF
listener but hang onto the CSA storage for reuse.  If recording is requested
again, reuse the same CSA storage.  This eliminates both the cycles used by
the unnecessary listener and the possible fragmentation of CSA storage.  It
does tie up the CSA storage until the server terminates however.

Chuck Arney
Arney Computer Systems

-----Original Message-----
From: IBM Mainframe Discussion List [] On Behalf
Of Phil Smith
Sent: Thursday, June 07, 2012 4:20 PM
Subject: ENF Listener usage

We have a long-running Started Task that controls the use of an ENF listener
for SMF interval record collection with an operator command.  The ENF
listener requires use of CSA storage.

When the Started Task receives an operator command to start SMF interval
processing it allocates CSA storage, registers the ENF listener, and WAITs
for interval expiration.

The question is: what should it do when the operator command says to stop
SMF interval processing?

The options seem to be:

1)      Deregister the ENF listener and free the CSA storage, meaning an
operator can switch SMF interval processing on and off, causing CSA storage
to be allocated and deallocated, possibly fragmenting CSA storage.  But when
we aren't collecting SMF interval data, we won't have an ENF listener

2)      Leave the ENF listener registered, but stop writing records when the
interval expires. Don't stop the ENF listener and free CSA until the Started
Task terminates (or possibly a special operator command like /f stcname,SMF
STOP).  This approach is easier on CSA allocations for the case where the
operator is switching SMF interval collection on and off.  But it leaves an
ENF listener registered when one is not needed.

Which approach have you seen? Which is "better" (and why)?

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