Allocating and Formatting Files › Formatting Files

Formatting Files

What Formatting Means

Formatting means initializing database or disk journal files into database pages or blocks according to information provided by the DMCL.

Important! NEVER format native VSAM files

Formatting Database Files

When you issue a FORMAT command against a database file, CA IDMS/DB:

• Establishes space management pages (SMPs) for the area(s) that map to the file
• Initializes the space management entry for each database page
• Establishes a header and footer on each database page
• Sets all data portions of database pages to binary zeros

Formatting Journal Files

When you issue a FORMAT command against a disk journal file, CA IDMS/DB formats the file into blocks according to the journal file specification in the DMCL module. The disk journal file contains:

• Journal header records at the beginning
• Binary zeros in the remainder

Before You Begin

Before you format a file, the DMCL that contains the file definition must be available. The DMCL provides the information CA IDMS/DB needs to format the file into database pages or journal file blocks.

Formatting Options

You can specify four options on the FORMAT utility statement. The following table identifies when to use these options:

Note: VSAM database files can only be formatted using the AREA option.

Example

The following example instructs CA IDMS/DB to format all the database files contained in segment EMPSEG:

format segment empseg;