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Small Changes in Recent z/OS Releases Can Result in Big Improvements

Why do only some release enhancements get splashy attention when other, smaller items are just as fabulous? I’ve found many functions over the past several z/OS* releases that system programmers may not have realized were there. In fact, many of these items were the result of customer requirements, making their delivery even more important.

Many of these enhancements are on releases your enterprise may already be running. They’re easy to implement, meaning that you can take advantage of them right away.

z/OS V2.1

Dynamic SYSDSN ENQ downgrade: This is the capability to allow a SYSDSN enqueue downgrade for batch jobs when appropriate. When a step has completed in the batch job and all of the subsequent steps of the job only need an exclusively held data set as a shared enqueue, the enqueue can be downgraded. This allows other jobs that may need the data set with a shared enqueue the possibility to execute. Better batch parallelism could result.

Parallel batch recall: Prior to z/OS V2.1, any migrated data sets were recalled serially at the job step level. As of this version, you have the option of indicating whether to recall all migrated data sets in the job step in parallel. Doing so reduces the delay for other jobs to use that initiator and may allow for better parallelism of batch execution.

TCP/IP profile syntax check: Checking the syntax of profile configuration steps could be cumbersome in TCP/IP. The configuration information could be extensive and you want to know that your changes were syntactically correct before using them. As of z/OS V2.1, the command VARY TCPIP,,SYNTAXCHECK,dsname can do that work for you. You will need CONTROL access to the OPERCMDS class profile MVS.VARY.TCPIP.SYNTAXCHECK. For best results, use the command on any TCP/IP stack that is at the same release as the profile statements in the data set for consistency, but it doesn’t have to be the same stack that will use that profile configuration.

Interactive System Productivity Facility (ISPF) swapbar customization: Since z/OS V1.10, swapbar is nifty for point-and-shoot session navigation, but it can get “lost” on a busy panel. z/OS V2.1 allows you to customize the swapbar with a divider line and session coloring and highlighting so it’s easier to notice for current and other sessions.

z/OS V1.13

Prevent content overlay during mount: Have you lost updates to files because they were over-mounted? Do you want the system to let you know when you’re mounting over something? Now you can have the system warn or even deny a mount on a mount point that’s not empty. Specify WARN or DENY (default is NOWARN, same as today’s behavior) on BPXPRMxx or on SETOMVS NONEMPTYMOUNTPT statement. D OMVS,OPTIONS shows the current setting.

Nonprivileged user mounts: Within certain conditions, users can have the capability to mount their own file systems, which is more restrictive than the SUPERUSER.FILESYS.MOUNT capability that exists. The nonprivileged user capability is exploited with the SUPERUSER.FILESYS.USERMOUNT UNIXPRIV profile, and BPXPRMxx MAXUSERMOUNTSYS and MAXUSERMOUNTUSER controls.

Marna Walle is a senior technical staff member within IBM’s Systems and Technology Group. Marna can be reached at

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