Making Temporary Modifications to the Catalog Environment

Operator Commands Discussed in This Section:

MODIFY CATALOG,ALIASLEVEL
MODIFY CATALOG,ALLOCATE
MODIFY CATALOG,CATMAX
MODIFY CATALOG,CLOSE
MODIFY CATALOG,{ISC|NOISC}
MODIFY CATALOG,{SYS%ON|SYS%OFF}
MODIFY CATALOG,TASKMAX
MODIFY CATALOG,UNALLOCATE
MODIFY CATALOG,{VLF|NOVLF}
MODIFY CATALOG,ENABLE(DELFORCEWNG)
MODIFY CATALOG,ENABLE(DSNCHECK)
MODIFY CATALOG,DISABLE(DELFORCEWNG)
MODIFY CATALOG,DISABLE(DSNCHECK)

The MODIFY CATALOG command allows you to alter a number of attributes that are initialized at IPL time. Many of these attributes are initialized by the SYSCATxx member of SYS1.NUCLEUS. The maximum catalog value (CATMAX) is also set at IPL time to 1024.

The parameters discussed in this section allow you to tailor your system according to temporary needs, without requiring you to bring down your system and IPL using a different SYSCATxx member. Other parameters allow you to gain closer control over storage, so that you can free up storage used by catalog management for your own jobs.

Table 1 gives an overview of the temporary system tailoring capabilities of the MODIFY CATALOG command.

Table 1. Temporary System Tailoring Capabilities of MODIFY CATALOG
Option	Purpose
ALIASLEVEL	To change the number of qualifiers used to determine the alias of a user catalog. This is the multilevel alias search level.
ALLOCATE	To allocate a catalog to the catalog address space. Using the NOISC or NOVLF subparameters, you can prevent the allocated catalog from using the specified cache.
CATMAX	To close all open catalogs and set a maximum to the number of catalogs that might be open in CAS. When the maximum is reached, the least recently used catalog is closed. This conserves storage.
CLOSE	To close a catalog and remove it from CAS, and to free up the CDSC or ISC storage used by the catalog.
DISABLE	To disable specific optional features. See the discussion of the DISABLE keyword for features that can be specified.
ENABLE	To enable specific optional features. See the discussion of the ENABLE keywords for features that can be specified.
ISC and NOISC	To either place a catalog in the in-storage catalog cache, or remove it from that cache.
SYS%ON and SYS%OFF	To either activate or deactivate the SYS% facility, to convert searches for SYS% data sets to searches for SYS1 data sets.
TASKMAX	To specify an upper limit to the number of service tasks to process catalog requests. Once the limit is reached, new requests must wait. Setting an upper limit reduces the storage used by CAS.
UNALLOCATE	To close and unallocate a catalog from CAS, and to free up the CDSC or ISC storage used by the catalog.
VLF and NOVLF	To either assign a catalog to the catalog data space cache, or to prevent placement of additional records from a catalog into that cache. Records are not removed from the CDSC with these parameters.
Note: This table does not reflect the detailed syntax of these commands. See MODIFY CATALOG Command Syntax for syntax information.