Use the following syntax when calling your OPS/REXX program:
If using OPSIMEX/OI:
ADDRESS OSF "OI PROGRAM(pgmname) WS(5000000)"
If using OPSEXEC/OX:
ADDRESS OSF "OX PROGRAM('library(pgmname)') WS(5000000)"
In the above examples the value of 5000000 (5Mbytes) is just an example.
Note: the keyword PROGRAM is required when allocating a bigger work space.