Mainframe, MVS and zOS Discussion

What is CATALOG,MASTER CATALOG and USER CATALOG? I read about them but it looks like all is same.

I think, I've confused myself - can someone please explore.

A CATALOG contains pointers to data sets and basically consist of data set names and volume serials; the term is not specific as to which type of catalog is being used. The MASTER CATALOG is defined during the IPL process and contains pointers to system data sets required during the IPL process. USER CATALOG is a catalog defined in the MASTER CATALOG that points to user (i.e., application) data sets. A system has one MASTER CATALOG but potentially many USER CATALOG's (typically, one for each application but this is somewhat site-specific and may be handled in another way in some sites). When creating a new data set, a catalog entry is defined -- otherwise, every data set reference would require DSN=,DISP=,UNIT=,VOLSER= in your JCL instead of just DSN=,DISP=.

You said USER CATALOG points to a application, does that mean a USER CATALOGs ate not defined for individual users?

Most sites define user catalogs for applications -- and at many sites, multiple applications will share a user catalog. The "user" in "user catalog" does NOT refer to a TSO user; usually all TSO users will be defined through a single user catalog. While a user catalog could be defined for each TSO user, that would complicate the catalog structure and slow down the system due to the large number of user catalogs defined.

strongly suggest to meditate on
http://www.redbooks.ibm.com/abstracts/sg246366.html
and
http://www.redbooks.ibm.com/abstracts/sg246105.html

and after that proceed to
http://www.redbooks.ibm.com/abstracts/s ... .html?Open

Thanks Robert and Enrico.