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LongEx Mainframe Quarterly - Nov 2018


A Fresh Look at Exits

Not the normal exits you think of when there's a fire in the building. In z/OS terms, an Exit is a hook we can use to insert our own code into the normal processing of z/OS and other systems. This month, we're taking a look at these Exits.

In our management article, we go back to the basics, and explain for beginners exactly what Exits are, and why they're used. We go a little deeper in our technical article , and discuss five best practices for Exits.

Finally in our opinion article, we argue that SMP/E usermods are ideal for managing many exits, but not all.

We hope you enjoy this issue.

management: A Beginners Guide to Exits

If you're currently upgrading your system to z/OS 2.3 system, you'll be working through all of the migration steps that are published by IBM.

One of these steps is "Examine your IEFUSI exit routine for possible changes." And it won't have been the first time you've heard the term "exit." But what are these exits, and why do we have them?


technical: Exits: My Five Best Practices

Over the past few months I've been working with a client on an exit: a hook we can use to tailor processing to our needs. This particular user had a problem: they'd lost the source code to the exit. They had some older source, but it didn't match what was running. So, we've been trying to recreate the current processing, and do some other fixes so it works with the latest software.

This is not the first time I've seen exit source code lost. Nor is this the first time I've seen clients get into trouble with exits. I've seen exits that are slow, use too much CPU, don't quite work the way they're supposed to, or cause problems when something goes wrong. There are ways to avoid these problems, including following what I consider to be best practices for implementing and maintaining exits. In this article, I'm going to talk about my five most important practices when using exits.


technical: Should We Package All Exits Using SMP/E?

Few sites will be without at least a couple of site-written exits: code that executes inside 'hooks' with z/OS or associated subsystems. When I first started as a systems programmer, our exits were packaged as SMP/E usermods. Today, many sites don't do this, and simply store the exit code in a PDS, or their source code management system like CA Endevor.

So, is this a good idea, or are these sites flirting with disaster?



LongEx Quarterly is a quarterly eZine produced by Longpela Expertise. It provides System z Mainframe and z/OS related articles for management and technical experts. It is published every November, February, May and August.

The opinions in this article are solely those of the author, and do not necessarily represent the opinions of any other person or organisation. All trademarks, trade names, service marks and logos referenced in these articles belong to their respective companies.

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