You can process VSAM entry-sequenced, key-sequenced, and relative-record data sets in Enterprise COBOL only after you define them through access method services (IDCAMS).
A VSAM cluster is a logical definition for a VSAM data set and has one or two components:
Use the DEFINE CLUSTER access-method services command to define VSAM data sets (clusters). This process includes creating an entry in an integrated catalog without any data transfer. Define the following information about the cluster:
Depending on what kind of data set is in the cluster, also define the following information for each cluster:
DEFINE CLUSTER NUMBERED RECORDSIZE(n,n)
When you define a data set in this way, all records are padded to the fixed slot size n. If you use the RECORD IS VARYING ON data-name form of the RECORD clause, a WRITE or REWRITE uses the length specified in DEPENDING ON data-name as the length of the record to be transferred by VSAM. This data is then padded to the fixed slot size. READ statements always return the fixed slot size in the DEPENDING ON data-name.
DEFINE CLUSTER NUMBERED RECORDSIZE(avg,m)
The average size COBOL record expected must be less than the maximum size COBOL record expected.
related tasks
Creating alternate indexes
Allocating VSAM files
Specifying relative organization for VSAM files
related references
z/OS DFSMS: Access Method Services for Catalogs