udp and receive buffering

Does anyone know if it is possible to buffer datagrams on a udp
connectionless socket ? I am currently running qnx 4.25 with tcpip 5.0,
with receive socket buffers sized to 240*1024 which seems to be the maximum.
Despite this, there is no evidence using either netstat -an or MSG_PEEK that
there is ever more than one datagram in the socket buffer prior to a read,
even though many datagrams are being sent to the socket.