Currently, the Network Server and Network Client use a 32K blocksize when
returning database data in QRYDTA blocks.
I came across the following statement in the DRDA spec (Volume 1, page 12):
Blocking applies only to the QRYDTA reply objects. Each
query block is a QRYDTA DSS. The maximum query block size
value allowed in the qryblksz parameter is increased from
32K to 10M, thus accomodating the larger data volumes
required by modern, more data-intensive applications.
The importance of larger block sizes depends strong on the application
profile.. For example, many applications perform single-record selects,
and they are not influenced by the block size.
But for some applications, it seems like the ability to use a larger block
size could be quite valuable.