Specifies the number of row caches for which slots are reserved
    in the database.

    You can use the RESERVE CACHE SLOTS clause to reserve slots in
    the database root file for future use by the ADD CACHE clause
    of the ALTER DATABASE statement. You can only add row caches if
    row cache slots are available. Slots become available after a
    DROP CACHE clause or a RESERVE CACHE SLOTS clause of the ALTER
    DATABASE statement.

    The number of reserved slots for row caches cannot be decreased
    once the RESERVE clause is issued. If you reserve 10 slots and
    later reserve 5 slots, you have a total of 15 reserved slots for
    row caches

    If you do not specify the RESERVE CACHE SLOTS clause, the default
    number of row caches is one.

    Reserving row cache slots is an offline operation (requiring
    exclusive database access). See the CREATE CACHE clause for more
    information.