The assembler can optionally align your data on natural
    boundaries. While disabled by default, this feature is
    enabled with the /ALIGNMENT=DATA command-line qualifier or the
    .ENABLE ALIGN_DATA directive. A natural boundary is an address
    that is evenly divisibly by the size of the scalar data type
    being accessed. The MACRO-64 automatic data alignment feature can
    automatically align word, longword, quadword, and octaword data
    to a natural boundary. Accessing data on a natural boundary can
    be significantly faster than an unaligned access.

    When the MACRO-64 automatic data alignment feature is enabled,
    the assembler automatically aligns all data-storage directives to
    a natural boundary. To achieve alignment, the assembler pads
    with 0 bytes as necessary before allocating the storage for
    the data directive. Labels that occur before the data-storage
    directive are defined to be the address of the data storage after
    alignment.