VSAM - Opening a loaded file (a file with records)

Opening a loaded file (a file with records)

Enterprise COBOL for z/OS, Version 4.2, Programming Guide

To open a file that already contains records, use OPEN INPUT, OPEN I-O, or OPEN EXTEND.

If you open a VSAM entry-sequenced or relative-record file as EXTEND, the added records are placed after the last existing records in the file.

If you open a VSAM key-sequenced file as EXTEND, each record you add must have a record key higher than the highest record in the file.