Coding input and output statements for VSAM files

OPEN

To connect the VSAM data set to your COBOL program for processing.

WRITE

To add records to a file or load a file.

START

To establish the current location in the cluster for a READ NEXT statement.

START does not retrieve a record; it only sets the current record pointer.

READ and READ NEXT

To retrieve records from a file.

REWRITE

To update records.

DELETE

To logically remove records from indexed and relative files only.

CLOSE

To disconnect the VSAM data set from your program.

All of the following factors determine which input and output statements you can use for a given VSAM data set:

• Access mode (sequential, random, or dynamic)
• File organization (ESDS, KSDS, or RRDS)
• Mode of OPEN statement (INPUT, OUTPUT, I-O, or EXTEND)

The following table shows the possible combinations of statements and open modes for sequential files (ESDS). The X indicates that you can use a statement with the open mode shown at the top of the column.

The following table shows the possible combinations of statements and open modes that you can use with indexed (KSDS) files and relative (RRDS) files. The X indicates that you can use the statement with the open mode shown at the top of the column.

The fields that you code in the FILE STATUS clause are updated by VSAM after each input-output statement to indicate the success or failure of the operation.