Reserve=number-journals

    Reserves additional space in the after-image journal
    configuration for the specified number of .aij files. You can
    specify the Reserve qualifier only when users are detached from
    the database. If you do not specify the Reserve qualifier, no
    space is reserved for additional .aij files.

    Note that you cannot reserve space in a single-file database for
    .aij files by using this qualifier with the RMU Set After_Journal
    command. After-image journal file reservations for a single-
    file database can be made only when you use the RMU Convert, RMU
    Restore, or RMU Copy_Database commands.

    Note that once you reserve space in the journal configuration
    (using the Reserve=n qualifier), the reservations are permanent.
    There is no way to unreserve this space unless you back up and
    restore the database. Specify fewer reservations with RMU Restore
    command After_Journal qualifier.

    Each reservation uses two blocks of space in the root file and
    the run-time global sections.

    When you reserve journals slots to create additional journals
    for your journal system, the reserve operation is not journaled.
    Therefore, you should perform a full database backup operation to
    ensure database consistency.