As documented elsewhere, under Enterprise PL/I, the FIXEDOVERFLOW/NOFIXEDOVERFLOW (or FOFL/NOFOFL) prefix applies only to FIXED DECIMAL operations.
However, it should also be noted that the (NO)FOFL prefix when applied to a PROCEDURE or BEGIN statement applies only to that block and to the blocks statically contained within it. The prefix does not apply to any other code dynamically called from within these blocks.
Similarly, if the (NO)FOFL prefix is applied to a CALL statement or a statement containing a function invocation, the setting in the prefix does not apply to the code in the invoked routine: it applies only to any FIXED DECIMAL calculations before or after the routine is invoked.