CA-L-Serv › Configure VTAM Communication › Configure Data Transmission Values for VTAM Communication › Determine the Best Buffer Size

Determine the Best Buffer Size

Make your transmission buffers large enough to hold an average piece of transmitted data (not the largest piece of transmitted data). Do not make buffers too large, as this wastes storage space. Use the same buffer size on all systems.

By default, CA-L-Serv uses 4-K buffers. To determine what buffer size you need, look at the types of data that CA-L-Serv is transmitting and the number of clients transmitting data through the same communications server:

• If the clients are transmitting small pieces of data, 1-K or 2-K buffers can be appropriate.
• If the clients are transmitting large pieces of data (for example, records from a file), you need larger buffers. For the files, look at the LRECL values for this data on a file by file basis to estimate the best buffer size.
• If several clients are using the same communications server, weigh the needs of all of those clients. You cannot set different buffer sizes for different clients, so estimate the best overall buffer size.

See the client documentation for more recommendations on the optimal buffer size.

Note: If you are using LU 0, the buffer size must not exceed the maximum transmit size that the VTAM path allows or all sends and receives fail.