not enough memory in /tmp for ontape -r

I was trying to restore a test database using ontape. It went fine when I just restored off the system tape (ontape -s -L 0), but I encountered problems whenever I tried to restore the logical logs. I ran out of room in /tmp and the restore just came to a halt! Is there a way to specify a different location for ontape to use? Also, is there a way to know how much memory ontape is going to need? Answers to either of these questions w/d be greatly appreciated!