Extent=number-blocks

    Sets the size, in blocks, of the default .aij file extension.
    This qualifier has no effect on fixed-length .aij files. This
    qualifier can be used while users are attached to the database.

    The minimum valid number-blocks value is 512. The default is also
    512.

    If the Extent qualifier is omitted, the default extension remains
    unchanged.

    See the Oracle Rdb Guide to Database Maintenance for guidance on
    setting the extent size.