I don't know what function you are calling but I assume that you want to wait for a specific period of time in your REXX program (for whatever strange reason).
I prefer this approach to wait for 1 second:
call syscalls 'ON'
address syscall 'SLEEP 1'
That is easy to understand and does not rely on any additional software than pure REXX.
By the way: In my opinion a request for a WAIT is in nearly every case a strong indication of poor (or at least inappropriate) design. Please rethink your approach.