The REXX PULL and PARSE EXTERNAL terminal I/O input statements
use CICS Terminal Control support to provide simulated line-mode input.
Note: - PULL (or PARSE PULL) first attempts to pull a line from the program
stack and, only if it is empty, issues a read to the terminal.
- Attempting to perform terminal line-mode input from a REXX exec
that is running as part of a non-terminal attached transaction, is
an error, which causes the exec to terminate with an error message.