Problems with the size of a select parameter?

Hi,

I'm trying to do the following: with a JDBC call

Statement.executeQuery("select sp_update(val1, val2, val3, val4);

sp_update is a stored procedure. This all seems to work fine with
PostrgreSQL 7.3 but with 7.2 I get a problem when val4 is ~2k. With
smaller amounts of data ~1k it works. I haven't tested to see what the
exact size is that fails yet.

I've searched around to try to find some reference to this issue but
didn't find anything. If I missed looking someplace please let me know
so I can do so in the future.

Thanks in advance.