Re: Activation Groups, yesterday and now?

When a job ends, all resources tied to job will be reclaimed.

There are some resources tied to activation group like memory, and there
are some resources tied to job, like socket descriptors.

If you have programs calling other programs within the job and there is
lots of pre-initialization that is done (e.g. building tables or objects
within memory) that may be used independent of who calls your program
within the job, and you do not want to incur the performance penalty of
always initializing on each call, then you would want to use activation
groups.

I also know Db2 processing has some things tied to activation groups such
as commitment control, but I am not an expert in this area.



"MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> wrote on 02/17/2020
04:09:23 PM:

From: Patrik Schindler <poc@xxxxxxxxxx>
To: Midrange Systems Technical Discussion

<midrange-l@xxxxxxxxxxxxxxxxxx>

Date: 02/17/2020 04:09 PM
Subject: [EXTERNAL] Activation Groups, yesterday and now?
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxxxxxxxx>

Hello folks,

as far as I understand, activation groups are kind of a shared
memory area for multiple programs to be run in. Correct?

Years ago, I stumbled across a file pointer not jumping back to
*LOVAL, because the default compile option of ILE RPG (at least with
V4) was DFTACTGRP(*YES). Obviously, certain attributes of programs
will be retained between runs. That's when I started to always use
DFTACTGRP(*NO) ACTGRP(*NEW) when compiling.

I'm very used to the concept in "common" operating systems that if
you end a program, used resources are claimed back by the OS and
said compiler options force this behaviour.

Now I wonder, what are activation groups actually good for? Or, have
been good for 30 years ago? What's the benefit in putting a bunch of
programs into the same (named, or default) activation group today?
Is it "just" for omitting the overhead for repeated program
activation between runs? Even on my ancient 150, programs are
starting blazingly fast.

I have a dim idea what "activation" does. AFAIK it's tied to the SLS
peculiarities. An unactivated program is just an ordinary object at
some address in the vast memory space. An activated program has
associated certain resources, so it is actually able to run and do
stuff. (At least that's what I understand from reading https://
www.ibm.com/support/knowledgecenter/ssw_ibm_i_72/ilec/ileacpa.htm)

Correct?

I've been reading through some resources at the internet but there
was none which gave clear answers to my above questionary. Most of
them also are a bit dated.