The FILEMSGS option
applies to physical files that are referenced in either a FILENAME
statement or function or in a LIBNAME statement or function.
If FILEMSGS is in effect
and you try to assign a data set that is allocated to another user,
SAS generates detailed error messages explaining why the allocation
failed. Under TSO, the messages are written to the display. The display
is cleared and the messages appear. You must press ENTER to return
to your session in the windowing environment. In batch mode, the messages
are written to the job log.
If NOFILEMSGS is in
effect, you still receive some error messages in your SAS log, but
they might not be as detailed.