Variable blocked LXX for CA Datacom/DB cannot be used with COVERED Master List Parameter

Document ID : KB000054766
Last Modified Date : 14/02/2018
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Description:

This applies to the z/OS operating system only.

One of the features added to Service Pack 2 (SP02) of CA Datacom/DB r11 is the possibility of a variable block-formatted LXX. As described in Section 1.1 (page 1-4) of the CA-Datacom Database Release Summary:

Variable logging is available at Version 11.0 SP2. The benefits of variable logging are reduced elapsed times for most update applications and reduced LXX write and read I/O. The CPU cost of using variable logging is about the same as using fixed logging.

CA recommends Variable Logging as the preferred choice because of the increased efficiencies. However, use of the Variable Logging feature means that the LXX cannot be Covered (using Multi-User Startup Parameter COVERED LXX).

Solution:

  1. As of SP02 of CA Datacom/DB r11, the LXX can be Variable-block formatted to provide significant enhancements to processing. In order to take advantage of this capability, the LXX will need to be redefined and initialized. Please refer to the DBUTLTY Reference Guide z/OS, Section 17.4 for details. Please note that to provide backward compatibility, the default for the LXX is Fixed format; to define the LXX as Variable-blocked will require the use of the ",VARIABLE=YES" parameter on the INIT LXX command.

  2. Please note the following restrictions and requirements as noted in the DBUTLTY Reference Guide z/OS Section 17.4:

    1. With variable logging, the block size must be set to 32760.
    2. This option is available for all DASD, except that in VSE a device definedĀ  as FBA may not be initialized as variable.
    3. Spanned logging cannot be used for a variable LXX.
    4. Variable logging is provided for the LXX. It is not supported for the Force Area (FXX). The FXX does not need to be initialized, however, when fixed logging is converted to variable logging.
    5. A variable LXX must be at least 250 tracks.

  3. As noted earlier, use of the Variable-blocked LXX precludes use of the MUF Startup option COVERED LXX. However, this option will continue to be available to users of Fixed-block LXX formats.