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XCA subsystem control

The PACLOG product uses BMC Extended Compression Architecture (XCA) subsystems to implement log compression.

A major advantage of using subsystem architecture is that virtual storage requirements in user address spaces are significantly reduced. PACLOG requires two OS/390 subsystems—the BMC Primary Subsystem (BMCP) and the BMC Consolidated Subsystem (BCSS). PACLOG can share these subsystems with other BMC products.


If PACLOG does not share these subsystems with other products, or if it shares them with only noncompression products, you might be able to improve PACLOG operation in your system. For more information, see PACLOG processing only (PPO) mode.


If PACLOG does share the subsystems with other products, be aware that some of the subsystem control commands that are discussed in this section may affect those BMC products. Refer to the documentation for those products for more information.

You must use a one- to four-character name to identify the BMCP and the BCSS subsystems to OS/390. The install system uses the default names BMCP and BCSS. If either name conflicts with a non-BMC subsystem installed on your system, you can use the SUBSYSID parameter in the BMCP or BCSS startup procedure to change the subsystem names.


If you change a subsystem name after the subsystem starts, you must perform an IPL.

In routine PACLOG operations, the XCA compression subsystems do not require your direct intervention.

The choices you make during PACLOG installation provide the required defaults for your environment. However, in some circumstances, such as a system initial program load (IPL), you may need to perform shutdown and restart procedures for these subsystems.

The install system tailors two subsystem procedures: one to start BMCP (default procedure member name BMCBMCP), and one to start BCSS (default procedure member name BMCBCSS). Each procedure contains the required parameter and statements for the subsystem. If either default name conflicts with the name of another procedure member, you can provide a different member name during installation.

Because the BMCP and BCSS subsystems are maintained independently of PACLOG, their maintenance levels do not correspond to the maintenance levels of PACLOG. When you install a new or updated BMC product that uses the BMCP and BCSS subsystems, use the Installation Check program to determine the level of the existing subsystems against the level of the subsystems from the distribution tape. Always use the highest level of subsystem code that is available.


The default names for the started tasks that correspond to the BMCP and BCSS subsystems are BMCBMCP and BMCBCSS, respectively. To use other names, change them when you copy them to an OS/390 started tasks library.

The commands used in this section are a subset of the DATA ACCELERATOR Compression (DAC) product commands. For a complete list of DAC commands, see the DATA ACCELERATOR Compression documentation .

This section contains the following topics:

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