Performing file I/O

CLISTs can perform I/O to a physical sequential data set, a member of a partitioned data set (PDS), or the terminal when allocated to a file. Four CLIST statements are available for opening, reading, writing, and closing files:

OPENFILE opens a previously allocated file for input, output, or updating. You may have allocated the file using the TSO/E ALLOCATE command or using step allocation (JCL statements in a logon procedure).
GETFILE reads a record from a file opened in the same CLIST.
PUTFILE writes a record to a file opened in the same CLIST.
CLOSFILE closes a file opened in the same CLIST.

Whenever a CLIST performs I/O, include an error routine that can handle end-of-file conditions and errors that may occur. End-of-File processing shows a CLIST with an error routine that handles end-of-file conditions.

Whenever CLISTs are nested, corresponding OPENFILE, GETFILE, PUTFILE, and CLOSFILE statements must be in the same CLIST.