For a key-sequenced data set, the total minimum buffer requirement is three: two data buffers and one index buffer. For an entry-sequenced data set, two data buffers are required.

If the number of buffers specified in the BUFND and BUFNI subparameters causes the virtual storage requirements to exceed the BUFSP space, the number of buffers is reduced to fit in the BUFSP space.

If BUFSP specifies more space than required by BUFND and BUFNI, the number of buffers is increased to fill the BUFSP space.