SNDPGMMSG to show message while something is running...

Trying to use SNDPGMMSG in a CL program that gets run interactively to flash
a message on the message line while the program is still running.  As an
example of what I'm attempting to accomplish, the CPYF command does this
with message:

  Copying member or label CMMAST in CMMAST in DUROLIB.

It appears on the message line as long as the CPYF command is running.  But
I haven't figured out how.  Using SNDPGMMSG, I've tried:

ToPgmQ( *Prv )  MsgType( *Info )
ToPgmQ( *Same ) MsgType( *Info )
ToPgmQ( *Prv )  MsgType( *Status )
ToPgmQ( *Same ) MsgType( *Status )

None of the other options look like solutions.  Essentially, I'd like to do
this in CL:

SNDPGMMSG CPF9898 MsgDta('Program to match drawings is now running...')
CALL   MATCHDRWS
ENDPGM

I want the message to appear on the screen's message line as long as the
MATCHDRWS program is running.

tia,
db