memory usage

I have a Borland C++ program (running on NT server) which connects to
PostgresSQL (V6.5) via ODBC (V6.5). The program reads data file and
updates database at regular intervals. The program has close all
connections when execution finishes. 

This program seems to use a lot of the memory on the linux server, and
the memory doesn't seem to be released at the end of execution. The same
thing occurs when I try to connect to the database from MS Access via
ODBC. 

Could the problem comes from front-end program, the ODBC, the database
or any other source? Any idea?

The current solution is to reboot the linux server every now and then to
fix this problem. Of course this is a short term solution and I'm
looking for a permanent solution.

Thanks.