Controls the size of data that can be safely accessed from
  different threads.  You do not need to specify this option for
  local data access by a single process, unless asynchronous write
  access from outside the user process might occur.  The default is
  /GRANULARITY=QUADWORD.

  Data that can be written from multiple threads must be declared as
  VOLATILE (so it is not held in registers).  To ensure alignment in
  common blocks and derived-type and record structures, use the
  /ALIGNMENT qualifier.

  You can only specify one of the qualifier options.

  BYTE
    Ensures that all data (one byte or greater) can be accessed from
    different threads sharing data in memory.  This option will slow
    run-time performance.

  LONGWORD
    Ensures that naturally aligned data of longword size (4 bytes) or
    greater can be accessed safely from different threads sharing
    data in memory.

    When this option is in effect, attempts to access smaller size
    data or misaligned data can result in data items that are
    inconsistently updated for multiple threads.

  QUADWORD
    Ensures that naturally aligned data of quadword size (8 bytes)
    can be accessed safely from different threads sharing data in
    memory.  This is the default.

    When this option is in effect, attempts to access smaller size
    data or misaligned data can result in data items that are
    inconsistently updated for multiple threads.