wsize and rsize specify the buffer size to use for read and write request. For NFS Version 2 protocol, rsize and wsize are a multiple of 512 bytes, up to a maximum of 8192 bytes.

For the NFS server with Version 3 (or later) protocol, rsize and wsize are negotiated between the z/OS NFS client and the NFS server. The maximum buffer size that is supported in z/OS NFS client system is 32 KB. The negotiated read and write buffer size will be the smaller of the buffer size supported by the server and 32 KB (min(server_info, 32KB)).

The z/OS NFS client system will reduce the read or write buffer size when there is constraint on the storage resource.

When using NFS Version 3 (or later) protocol the system normally determines the optimal buffer values. However, if the number of retransmissions or the number of time-out from nfsstat report is high, reduce the write buffer size (wsize) to 8 KB to avoid retransmission of large 32 KB data.