z/OS DFSMS Managing Catalogs
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Identifying the Master Catalog and Initial Configuration (SYSCATxx)

z/OS DFSMS Managing Catalogs

Attributes Defined in SYS1.NUCLEUS(SYSCATxx)
  • Master catalog's volume
  • Master catalog type
  • SYS% facility on or off
  • Multilevel alias search level
  • Catalog address space service task lower limit
  • Master catalog name
  • Tape volume catalog high level qualifier
  • AUTOADD indicator
  • Start of change CAS Service Task Table Size (TASKTABLESIZE) End of change

Once you have defined your master catalog, and have cataloged the necessary system data sets in it, you must identify the master catalog to the system to use it as a master catalog. The SYSCATxx member of SYS1.NUCLEUS contains the information for identifying the master catalog to MVS™.

If you use the LOADxx member to identify the master catalog, the system uses the master catalog specified in the member, and the master catalog message is not issued.

You can have multiple SYSCATxx members. The default name is SYSCATLG. Each copy of the SYSCATxx member can identify different master catalogs.

The following is the format of the SYSCATxx member of SYS1.NUCLEUS (the member can contain only one record):

is the volume serial number of the master catalog's volume. This must be in the first 6 bytes of the record.

catalog type
is the catalog type and SYS% facility default, where:
blank or 0
Indicates a catalog master catalog. In this case, leave bytes 8, 9, and 10 blank. Only the volume serial number and the catalog name can be specified for a master catalog.
indicates a catalog, with the SYS% facility turned off,
indicates a catalog with the SYS% facility turned on.

This value must be defined in the seventh column of the record. The setting for the SYS% conversion facility can be changed after IPL for a current session with the MODIFY CATALOG,SYS% operator command.

alias level

specifies the multilevel alias search level. The default is 1 and the maximum is 4.

This value must be defined in the eighth column of the record. If you want the default value of 1, either specify 1 or leave the eighth column blank.

This value can later be changed for a current session with the MODIFY CATALOG,ALIASLEVEL operator command.

CAS task low limit

specifies the catalog address space service task lower limit (maximum number of CAS service tasks or requests), in hexadecimal. The value can range from X'18' to X'FF', but the default is X'3C'.

This value must be defined in the ninth and tenth columns. Specify the default value (either explicitly, or by leaving these two columns blank). If the catalog address space needs more services tasks, it creates them.

catalog name

specifies the name of the master catalog. The name can be up to 44 characters.

To change to a different master catalog, you must IPL the system and specify a different SYSCATxx member.

tape volume catalog high level qualifier (optional, otherwise blank)

specifies the first name qualifier of all volume catalogs (volcats) in the system. The value is specified as 1 to 8 characters. See Defining Names for a Tape Volume Catalog. Leave this blank if you have no tape volume catalog member.

AUTOADD feature (optional, otherwise blank)

specifies that the autoadd function is enabled when the first connection is made to the coupling facility by the catalog address space.

The value Y must be specified in column 63 of the record.

Start of change 65 End of change
Start of change TASKTABLESIZE (optional, otherwise blank)

is a three-digit decimal number that specifies the size of the service task table allocated by CAS in common storage. The maximum value is 400. If no value is supplied, or the value supplied is less than 200, a value of 200 is used.

  1. 10% of the service tasks specified are reserved for system use, such as recursive catalog calls resulting from the need to allocate catalogs for a request. The remaining service tasks are available for user catalog requests.
  2. This parameter cannot be specified in the SYSCAT entry of a LOADxx member.

TASKMAX, which you can specify in parmlib member IGCATxx or the Modify Catalog command, differs from this value in that it is a soft limit on the maximum number of concurrent non-CAS service requests that can be running at any given time and can be changed at any time. TASKTABLESIZE, on the other hand, can only be changed with an IPL. TASKMAX can be no larger than 90% of TASKTABLESIZE.

End of change
The following is a sample step to create the SYS1.NUCLEUS member SYSCATLG. This job describes a master catalog named SYS1.MASTERA.ICFCAT on volume SYSRES. The SYS% to SYS1 conversion facility is turned off. The multilevel alias search level is set at one. The catalog address space service task lower limit default of X'3C' is used by leaving columns 9 and 10 blank.
 //SYSUT1   DD *
 SYSRES11  SYS1.MASTERA.ICFCAT                                 y

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