Using VSAM as the access method

This topic contains Product-sensitive Programming Interface information.

You can allocate VSAM data sets by using the DEFINE CLUSTER command. You must specify the REUSE parameter when allocating HALDB data sets. Use of this command is described in z/OS® DFSMS Access Method Services for Catalogs.

Important: If you use the Database Image Copy 2 utility to take image copies of your database, the data sets must be allocated on hardware that supports either the DFSMS concurrent copy function or the DFSMS fast replication function.

When loading databases (excluding HALDB databases) that contain logical relationships or secondary indexes, DL/I writes a control record to a work file (DFSURWF1). This work file must also be allocated and in the JCL.

All other data sets are allocated using normal z/OS JCL. You can use the z/OS program IEFBR14 to preallocate data sets, except when the database is an MSDB. For MSDBs, you should use the z/OS program IEHPROGM.

For more information about the standard DFSMS methods for allocating data sets and about data sets in general, see:

z/OS DFSMS: Using Data Sets
z/OS DFSMS Access Method Services for Catalogs