/SIZE[=nnn]

    Specifies the amount of disk space (in blocks) that is usable for
    the file system. This value must be greater than the current
    logical volume size and less than or equal to the physical
    size of the disk or the expansion limit (specified by /LIMIT),
    whichever is smaller.

    If the value is omitted, the usable space is increased to the
    physical size of the disk or the expansion limit, whichever is
    smaller.