CA Dynam for VSE User Guide

Managing the VTOC
Default Allocation Support
You can specify a system default to allocate disk space globally. This default is
specified by the DEFALOC parameter of the DYNAM/D option record, and can
be used to simplify the creation of temporary or test data sets. To create the
default specification, add the DEFALOC parameter to the DYNAM/D option
record, and specify desired allocation information in it. For example:
DEFALOC(POOL01,100)
This sets a default allocation of 100 tracks primary allocation, with automatic
secondary allocation, to be taken from POOL01. To use the system default,
code a bare DLBL with a data set name which does not exist in the catalog; CA
Dynam/D will use the default allocation information to allocate the file.
The same procedure is used to input the file. In this fashion, a programmer
who needs temporary space can get it and use it without coding the EXTENT
information or creating a catalog entry.
// JOB TEST PROGRAM
// DLBL MYFILE,'TEST.FILE',30
// EXEC PROGRAM
/&
The example shown above causes CA Dynam/D to allocate 100 tracks from
POOL01 (the default setting) to TEST.FILE, and sets a retention period of 30
days. At the end of 30 days, the file would be automatically deleted.
Managing the VTOC
A volume table of contents (VTOC) contains entries made up of seven types of
data set control blocks (DSCBs) called format-0, format-1, ..., format-6
records. (The format-6 record is only used by OS systems.) These records
describe the type and location of data sets on a DASD volume.
CA Dynam/D VTOC management provides the following:
• Rotational Position Sensing (RPS) for CKD devices, significantly reduces
channel busy time. The VSE VTOC management routines do not use RPS.
• A software technique for position maintenance on FBA devices, eliminates
redundant reads of VTOC control intervals.
• VTOC indexes built on selected volumes and used for processing both
dynamic and nondynamic files, greatly reduce VTOC I/Os and channel
busy time.
4–10 User Guide