z/OS release
The version number of z/OS a system runs, such as 2.5 or 3.1, which IBM updates with a new release every two years.
Also written z/OS version, z/OS level, V2R5, z/OS 3.1, release level
z/OS is released in numbered versions. Older releases were written as V2R4 and V2R5, meaning version 2, release 4 or 5. Newer ones are written simply as z/OS 3.1 and 3.2. In recent years IBM has published a new release every two years.
Each release adds new functions and removes some old ones. IBM supports each release for several years, so sites do not have to upgrade every time. Most stay one release behind the newest, and plan an upgrade as a project, with testing on development systems first.
Between releases, the software is updated with fixes, PTFs, so two systems on the same release can still be at different service levels.
On a running system, the D IPLINFO command shows the release, and the information also appears in the system log at IPL. You will see release numbers in job ads, in software requirements, such as "needs z/OS 2.5 or later", and in IBM documentation, which is published separately for each release.
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- z/OSThe main operating system that runs on IBM mainframes, in the same way Windows or Linux runs on a laptop or server.
- SMP/ESystem Modification Program/Extended: the tool used to install and maintain z/OS and other software, keeping a record of every piece and every fix.
- PTFProgram temporary fix: a packaged fix from IBM for a problem in z/OS or another IBM product, installed with SMP/E.
- System programmerThe person who installs, configures, tunes and upgrades the operating system and its subsystems.
- Change controlThe process every change goes through before reaching production: reviewed, approved, scheduled and reversible.