Specifies SPAM thresholds for logical areas with uniform format
    pages.

    When you specify the THRESHOLD clause without enclosing it in
    parentheses, you are specifying the default threshold values
    for all areas specified in the ALTER STORAGE MAP statement.
    You cannot alter the thresholds for any storage areas which are
    part of the storage map. Only specify this clause for storage
    areas being added to the storage area by the ALTER STORAGE MAP
    statement.

    To specify threshold values for a particular storage area,
    specify the clause as part of the STORE clause and enclose the
    THRESHOLD clause in parentheses. You can only specify threshold
    values for new areas, not existing ones.

    For examples of specifying the THRESHOLD clause, see the Oracle
    Rdb Guide to Database Design and Definition. See the CREATE
    STORAGE_MAP statement for a description of the THRESHOLDS clause.