sockets question again

I apologize if this seems like a repeat post, but I never got a clear answer (this isn't a criticism, it's possible I'm not being clear enough)....I'm attempting to enlarge the socket buffers for a udg socket, but it seems that no matter how large I attempt to set the buffer with

setsockopt( )

I only am able to enlarge to a size of 262142 (according to getsockopt( ) ). What governs the amount of size you can allocate to a socket buffer, and how can I change it?

If it's possible, it will be a kernel tunable parameter. For example, see this.

Since "sysctl -a | grep udp_max_buf" didn't show anything, should I assume that this is not a tuneable parameter?

No, you should carefully read your docs for whatever os you are using. The names of kernel tunables are not controlled by a standard.