can't open more than 128 connections

hello,

I'm trying to open 300 connections to a database using Microsoft odbc
.NET and psqlodbc.  At the 129th connection attempt i get an
exception:

{"ERROR [IM005] [Microsoft][ODBC Driver Manager] Driver's
SQLAllocHandle on SQL_HANDLE_DBC failed" }
State: "IM005"

I know that my db can take over 300 connections without using the odbc
driver because i open 300 connections with psql with no problem.  Is
there some config param i need to set on the connection string so that
i can take more connections?  what am i doing wrong?

thank you, amir