When large blocks of data are used, more main storage is required than when smaller blocks are used, but large blocks save CPU time and disk space. ADDITIONALLY, extra buffers may save ELAPSED time since the program does not have to wait for an I/O to complete for it to CONTINUE processing.

In the JCL, you specify BUFNI (number of index buffers) and BUFND (number of data buffers) as sub parameters of the AMP parameter.

For random access, the BUFNI is one more than the number of index levels and a BUFND of 2 is FINE.

For SEQUENTIAL access, a BUFNI of 1 and a minimum of 5 for BUFND is fine.

For dynamic access, the values of each is the higher of the numbers for either random or sequential.

When large blocks of data are used, more main storage is required than when smaller blocks are used, but large blocks save CPU time and disk space. Additionally, extra buffers may save elapsed time since the program does not have to wait for an I/O to complete for it to continue processing.

In the JCL, you specify BUFNI (number of index buffers) and BUFND (number of data buffers) as sub parameters of the AMP parameter.

For random access, the BUFNI is one more than the number of index levels and a BUFND of 2 is fine.

For sequential access, a BUFNI of 1 and a minimum of 5 for BUFND is fine.

For dynamic access, the values of each is the higher of the numbers for either random or sequential.