...
>ANR0252E Error writing logical page 250880 (physical page 251136) to
>database volume /tsm/volumes/o00tsmtoe2-
>/stg01/dbvol00b.TSMTOFF00.
>ANR9999D Error writing to database logical volume.
>ANR7838S Server operation terminated.
>ANR7837S Internal error BUF087 detected.

Paul - The probably reason is outlined in the explanation of those messages in
       http://people.bu.edu/rbs/ADSM.QuickFacts

Root typically has high Unix Resource Limits (as per AIX /etc/security/limit)
while more mortal, non-root users do not.  Check this in your system for the
username which invoked TSM.  In whatever shell you are employing, use its
appropriate limits command to boost the limit to accommodate your file sizes.
Certainly, the filesize limit needs to be well over 2 GB.

   Richard Sims, http://people.bu.edu/rbs