S,
I do not recommend changing MASSD.
Actually, I do not recommend using the MASSD solution for your original problem, except as a temporary workaround. I still believe you should solve the root cause.
Changing MASSD is not a really a topic suitable for the APO forum. Technical questions are typically answered in an ABAP or other technical forum.
Of course, if you had actually searched SCN before asking about how to change MASSD, you probably wouldn't have needed to ask the question in the first place.
Best Regards,
DB49