CA Dynam for VSE User Guide

Selecting Logical Units
Selecting Logical Units
We recommend omitting any logical unit specifications from JCL for all files
processed under CA Dynam/D control. The following description explains how
CA Dynam/D selects logical units.
CA Dynam/D first decides on which physical device the file belongs. It then
begins searching for an appropriate logical unit. The order of priority for
choosing a logical unit is as follows:
• Logical unit as specified in the EXTENT statement
• Logical unit as specified with S:nnn option from DLBL statement
• Logical unit as found in user DTF
• Logical unit as defined for the data set in the Catalog
• Highest logical unit in the partition, if none of the above has been specified
The search for a logical unit ends when a valid LUB is found.
Overriding SYS Numbers
You can override the DTF or cataloged SYS number by using the DLBL file ID
option code S:nnn. The SYS NUMBER OVERRIDE option code must be enclosed
within parentheses as the last part of the file ID. Use the following format:
// DLBL FN,'file-ID (S:nnn)'
where nnn represents the logical unit number. Only programmer LUBs are
valid.
Specifying Other Option Codes
In conjunction with the S:nnn specifications, other option codes can also be
specified within the parentheses. For example, to specify that SYS005 is to be
used as the logical unit for the file and option codes D and I are also to be in
effect, submit this DLBL statement:
// DLBL FN,'file-ID (S:005,D,I)'
Chapter 4: Disk File Management 4–25