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IPL unit_address LOADPARM
where LOADPARM bytes contain:
bytes 1--4 5--6 7 8
┌──────────────┬────────────┬─────────────┬─────────────┐
│ IODF DASD │ LOADxx │PROMPT FEAT. │ ALT NUCx │
└──────────────┴────────────┴─────────────┴─────────────┘
IODF LOADxx prompt nucleus
device suffix feature suffix
number
See
Managing Catalogs
, SC26-4914, chapter 2. You must ensure that all OS/390
data sets required for IPL are cataloged in all catalogs that might be used as an
alternate master catalog. Other than content, there is no difference between a
user catalog and the master catalog. A catalog is the OS/390 master catalog by
virtue of the fact that it was designated as such during IPL.
The master catalog must be on a volume that is mounted and available at all
times. The master catalog should be password protected or secured via RACF.
This is to insure that user data sets are not cataloged in the master catalog and
to insure that end users cannot uncatalog critical system data sets.
Formerly, a single catalog could not serve as the master catalog for more than
one system at a time. However, a master catalog could be accessed from
another system as a user catalog.
You can now share a master catalog between multiple systems. See
Managing
Catalogs
, SC26-4914, chapter 2.
With the introduction of MVS/SP 5.1.0, an installation that has multiple MVS
images can share a master catalog and share an IPL volume among multiple
MVS images. The system data sets, SYS1.LOGREC and SYS1.STGINDEX are no
longer fixed named and unable to be shared. They can now be shared and
specified by the installation. In addition, a system symbolic, &SYSNAME, was
introduced and can be used as part of data set name specifications for some
parameters in PARMLIB. When you use &SYSNAME, data set name specification
becomes flexible and you do not need a separate parameter specification for
each system in the sysplex.
For example, we can specify the following LOGREC=SYS1.LOGREC.&SYSNAME.
The symbolic name, &SYSNAME can also be used in other PARMLIB parameter
specifications. You can use &SYSNAME for IEASYSxx parameters VIODSN=,
PAGE=, SWAP=, DUPLEX=, and NONVIO=. You can use &SYSNAME for
SMFPRMxx parameters DSNAME= and SID=. Catalog if it has been connected
to the second system′s master catalog via the AMS ″IMPORT CONNECT″
command.
5.6.3.2 OS/390 User Catalogs
User catalogs contain data set information for user data sets. They should be
created as ICF catalogs. VSAM user catalogs may be accessed during the
migration period, but should only be used if VSE access is required. They should
be converted to ICF catalogs once the migration is over.
Chapter 5. Disk and Tape Storage Considerations 115