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IBM z/OS 1.8: Features to look forward to and some to kiss goodbye

What's inside IBM's latest mainframe operating system, z/OS 1.8? Check out what expert Robert Crawford found and found lacking in IBM's latest offering.

Announced in August 2006 and available the following September, z/OS 1.8 is the latest and greatest version of our beloved mainframe operating system. While not a breakthrough release, it continues several trends from the last few years. There's more exploitation of the Z9 series processor along with additional enhancements to workload management. Also included is more support for industry standards especially from the open systems side.

We should begin by discussing what's not in this release. Nowhere in sight is relief for the 32K UCB (unit control block) address limit. Lots of system storage moves above the 2G bar but there's still no mention of executing code up there. And, if you're tired of your RACF database being a bottleneck you will have to continue being tired.

A lot of things get bigger with this release. z/OS 1.8 supports up to four terabytes (TB) of central storage on a Z9 processor, but less on other processor families. PDSE and GRS use 64 bit addressing for some blocks above the bar allowing for more parallel usage. The C/C++ runtime libraries support larger VSAM and QSAM datasets. There is also a change to the ENQ/DEQ interface allowing middleware that normally causes a lot of enqueues (e.g., CICS) to set limits higher than the system default. Lastly, the new operating system adds parallel vary online commands to previously supported simultaneous vary offline commands.

IBM continues to add support for current and evolving industry standards. Often mentioned is the new integrated XML parser. From the literature it appears this non-validating parser supports four different code pages and is provided as a callable service to any language that can invoke assembler subroutines. Look for other software to exploit this service as it is "intended for use" by system components, middleware and applications

IBM continues to load workload manger (WLM) with new functionality. A new interface allows subsystems to tell WLM when they aren't feeling well. This may be a boon to those of us who wish WLM would stop shoveling work to a CICS that has problems already. WLM also gets tighter integration with DB2 so it can advise the database management system (DBMS) how best to manage its buffers. z/OS 1.8 adds support for zIIP processors and enhances it for zAAP's. IBM continues the trend to envelop WLM into Enterprise Workload Management (EWLM) including what sounds like a nifty integration of RMF reporting into the Hardware Configuration Management (HCM) web user interface (WUI).

And, if you're tired of your RACF database being a bottleneck you will have to continue being tired.

System installation continues to get simpler. IBM's CustomPac provides a menu system for ordering IBM and ISV software in an integrated package. SystemPac provides a data facility data set services (DFDSS) logical volume dump allowing you to simply restore the installation materials to any volume you wish. Note, however, it also means you must a license for DFDSS to perform the restore. More products are added to the MVS health checking utility. The previously introduced configuration GUI's for Communication Server (CS) is extended to include quality of service (QOS) and intruder detection services (IDS).

Of course, you can't install a new release without kissing some things goodbye. IBM removed the firewall from integrated security services and advises customers to use equivalent functionality in CS. In addition, AnyNet is yanked as well as six of the seven plugins for msys for setup. More ominously, the z/OS 1.8 announcement declares that z/OS 1.4 and 1.5 will out of support by March 31, 2007. The migration path may not be pretty either as enterprises on 1.4 can only migrate in a single step to 1.7. However, those on 1.5 can get up to 1.8 in one go.

The mainframe operating system continues to evolve although perhaps not as quickly as we would wish. One problem may be the compatibility promise IBM made way back with the 360 systems. However, we will take incremental change when we can get it and have faith that IBM is working on the big problems and bottlenecks as we wrestle with them in the trenches.

About the author
Robert Crawford has been a CICS systems programmer off and on for 24 years. He is experienced in debugging and tuning applications and has written in COBOL, Assembler and C++ using VSAM, DLI and DB2.

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