Syntax options:

    MAXVALUE numeric-value | NOMAXVALUE

    The MAXVALUE clause specifies the maximum signed quadword
    (BIGINT) value that the sequence can generate. The numeric value
    must be between -9223372036854775808 and 9223372036854775808. The
    MAXVALUE must be equal to or greater than the value specified for
    the START WITH clause and greater than the value specified with
    the MINVALUE clause. The NOMAXVALUE clause specifies that the
    maximum value for an ascending sequence is 9223372036854775808
    (plus the cache size) and -1 for a descending sequence.

    The NOMAXVALUE clause is the default.