5. FILES › 5.2 VTOC/Catalog Activity Information Area Files › 5.2.1 Data Set Allocation File (VCADAA)

5.2.1 Data Set Allocation File (VCADAA)

FILENAME=VCADAA

The Data Set Allocation File describes the attributes,
allocation, and current status for each data set in the
installation.

This file is derived from data collected by the DASD Space
Collector (VCC).  One observation is built for each data set
on each volume selected for processing.  If a data set
resides on more than one volume, then that data set will have
more than one observation in the file.

Sources of data for the observations in this file are as
follows:

    1. The format-1 DSCB in the VTOC provides the data set
       name and most of the attributes of the data set.

    2. The SMS cells in the VVDS provide the SMS class name
       values for DATACLAS, STORCLAS, and MGMTCLAS constructs
       if the data set is SMS-managed.

    3. The storage group name is obtained by VCC from the SMS
       address space if available.

The VCA DAA file contains observations for both non-VSAM and
VSAM data sets.  For non-VSAM observations, the VCADAA file
is sole location of data, having been merged into a complete
observation from the above sources.

For VSAM observations, it is important to realize that the
data for the VCADAA file comes from the VTOC, not the
catalog.  With ICF catalogs, the VTOC is the definitive
source of information for the space allocated by a data set
(DAASPACA).  For this reason, the VCADAA file is perfectly
adequate for accounting applications for both VSAM and non-
VSAM. The utilization of space within an allocated extent is
not described in the VTOC for VSAM files; hence, when the
data set type (DAADSTYP) is VS (for VSAM), space used
(DAASPACU) is always set equal to space allocated (DAASPACA).
Yet, for accounting purposes, space allocated and its time-
oriented derivatives such as DAADURSP and DAAKBHR are always
sufficient.

Another reason why VSAM data is often better observed through
the VCADAA file is the maintenance of various fields by MVS
and DFP.  For example, the critically important element known
as date last-referenced (DAAREFDT) is more accurate when
obtained from the VTOC field known as DS1REFD.

Yet another reason why the VCADAA file should be considered
as a source of data about VSAM data sets is simply ease of
programming.  It is generally easier to report on data from
one SAS file if you are new to SAS programming.  Unless you
need detailed attributes unique to VSAM structures (number
of control-area splits (DAANCAS)), or you need utilization
statistics within the allocated space, you should consider
using the VCADAA file for all data set types due to the
simplicity of this approach.

The following sections describe the file's organization, list
the data elements maintained, and provide usage hints.

    1 - VCADAA File Organization
    2 - VCADAA Data Elements List
    3 - VCADAA Usage Considerations
    4 - VCADAA Retrieval Examples