Syntax option:

    DEPTH IS number-buffers BUFFERS

    Specifies the number of buffers to prefetch for a process.

    The default is one-quarter of the buffer pool, but not more than
    eight buffers. You can override the number of buffers specified
    in the CREATE or ALTER DATABASE statements by using the logical
    name RDM$BIND_APF_DEPTH.

    You can also specify this option with the DETECTED ASYNC PREFETCH
    clause.