I don't know about MVS, but on an AIX server you can use the 'no' (network
option) command to change the tcpip window sizes, as follows:

 no -o tcp_sendspace=32768
 no -o tcp_recvspace=32768

The default on my AIX server was 16K.  When we increased this to 64K,
however, our Macintosh clients started freezing up, so be forewarned.
We have an open incident on this problem.
..Paul

Paul Zarnowski                     Phone:   607/255-4757
Cornell Information Technologies   Fax:     607/255-6523
Cornell University                 US Mail: 315 CCC, Ithaca, NY 14853-2601
--
On Mon, 20 Nov 1995 14:38:39 +0500 Andy Raibeck said:
On Mon, 20 Nov 1995 14:38:39 +0500 Andy Raibeck said:
>Using a Sniffer, we've noticed that ADSM sends out packets, typically 598 or
>604 bytes in size. When we look at the packet in greater detail, the actual
>data portion is 536 bytes, with the remainder being protocol headers (LLC,
>DLC, IP, SNAP, etc.). This strikes me as a major bottleneck; that if I could
>send a smaller number of larger packets, I could improve performance by quite
>a bit (potentially). Oh, BTW I'm using TCP/IP for connectivity to an ADSM/MVS
>server.
>
>I use TCPBUFFSIZE 32 and TCPWINDOWSIZE 24, which are the only tuning options
>available in ADSM itself (for TCP/IP). IBM Level 2 tells me that the sizes
>must be set somewhere in the network or network card.
>
>Has anyone noticed this, and if so, can anything be done about it? I've seen
>this for NetWare and AIX. I haven't sniffed my other client types yet, but
>I believe I'd probably find something similar.
>
>Any help would be appreciated.
>
>Thanks,
>
>Andy Raibeck
>Connecticut Mutual
>203-987-3521