File Characteristics

Non-VSAM Files in z/OS

To create a non-VSAM file in z/OS, use a JCL statement or a facility such as TSO. The DCB characteristics of the file must be:

Parameter	Value
DSORG	PS or DA
BLKSIZE	Page size of the area(s) mapped to the file
RECFM	F

VSAM Files

To create a VSAM database or journal file, you use the IDCAMS utility from IBM. The following IDCAMS statements are used:

DEFINE SPACE—Allocates disk space for one or more VSAM files; alternatively, the database file can be defined in its own data space
DEFINE CLUSTER—Creates the database file as an ESDS VSAM cluster specifying the following attributes:

Attribute	Description
RECORDS	Assign: PRIMARY SPACE as the number of pages mapped to the file SECONDARY SPACE as the value 2
RECORDSIZE	Assign: AVERAGE as the page size of the area mapped to the file MAXIMUM as the page size of the area mapped to the file
CONTROL INTERVALSIZE	For database files,assign a value at least 8 bytes larger than the page size of the area mapped to the file, but less than twice the page size minus 8 ((2 * page size)- 8) For disk journal files, assign a value that is the same as the page size of the journal buffer
SHAREOPTIONS	Assign (3 3)
REUSE SUBALLOCATE or UNIQUE
NONSPANNED
NONINDEXED