large file limitation

I have installed Postgres 7.1.3 on a Solaris 2.8 machine.  When I dump
the database the file is larger than the 2 GB limit.  I checked with
our unix admin and he confirmed that Solaris 2.8 would not support
files larger than 2GB until he made a modification to use large files.
 He made the modification and we verified that the unix system could
handle files larger than 2GB.  I then dumped the database again and
noticed the same situation.  The dump files truncate at the 2GB limit.
 I suppose I need to recompile Postgres now on the system now that it
accepts large files.  Is there any library that I need to point to
manually or some option that I need to pass in the configuration?  How
do I ensure Postgres can handle large files (>2GB)

Thanks