Insert / Update Statement

I am updating my postgres database (Postgres 6.4 on Redhat 6) from a Windows client using Java and JDBC. Everything works fine, util one tries to insert large amounts of data into a fields. The error reported indicated that my SQL statement is to long. I have adjusted my code to update / insert data into one fields at a time, which resulted in many update / insert statements, and now I can insert more database, but still not enough.

Is there a way I can configure the maximum lenght of the insert statement, or that I can insert large amounts of data ?

Thanks
Alex