With XCF multipath channel attachment, VTAM® uses the MVS™ XCF signaling facility to send data to other hosts. By analyzing statistics provided by VTAM, you can select I/O buffer sizes and other options that can improve performance of these I/O operations. The amount of data that VTAM can read in one operation depends on the size of the read buffer.

Each tuning statistics record contains information about the state of data-transfer operations between two VTAMs (using multipath channel connections). Each record contains statistics that cover the time period since the last tuning statistics record was written for that multipath channel connection.