The Display Prompted Command function prompts for a command and uses the
returned string to 1) run the command via user specified QCMDEXC program, 2)
parse the returned string into 68 byte blocks to be displayed, printed, sent to
the job log, or written to a source member. Variables may be specified for the
parameters of the command to be prompted for and will be filled at execution
time. The variables must be declared in the program.