You can specify the number of I/O buffers that VSAM uses to transmit data between virtual and auxiliary storage.
A buffer is the size of a control interval in the data component. Valid values for the number of data buffers (BUFND) are from 0 through 65535. Minimum value is 1 plus the value specified for STRNO. If you omit STRNO, BUFND must be at least 2, because the default for STRNO is 1.
The minimum buffer specification does not provide optimal sequential processing performance. Generally, the more data buffers that are specified, the better the performance. Additional data buffers can benefit direct inserts or updates during control area splits and benefits spanned record accessing.
Maximum number of buffers is 255, which includes 254 data buffers and one insert buffer.