Terminal files

When you are running with the runtime option POSIX(OFF) under interactive TSO, z/OS® XL C/C++ associates streams to the terminal. You can also call fopen() to open the terminal directly if you are running under TSO (interactive or batch), and either the file name you specify begins with an asterisk (*), or the ddname has been allocated with a DSN of *.

When running with POSIX(ON), z/OS XL C/C++ associates streams to the terminal under TSO and a shell if the file name you have specified fits one of the following criteria:

Under TSO (interactive and batch), the name must begin with the sequence //*, or the ddname must have been allocated with a DSN of *.
Under a shell, the name specified on fopen() or freopen() must be the character string returned by ttyname().

Interactive IMS™ and CICS behave differently from what is described here. For more information about terminal files with interactive IMS and CICS see Using C and C++ standard streams and redirection.

If you are running with POSIX(ON) outside a shell, you must use the regular z/OS XL C/C++ I/O functions for terminal I/O. If you are running with POSIX(ON) from a shell, you can use the regular z/OS XL C/C++ I/O functions or the POSIX low-level functions (such as read()) for terminal I/O.