PACK

 cDEC$ PACK

 Specifies the memory starting addresses of derived-type items.  It
 takes the following form:

 cDEC$ PACK:[{1 | 2 | 4}]

   c        Is one of the following: C (or c), !, or *.

 Items of derived types and record structures are aligned in memory
 on the smaller of two sizes:  the size of the type of the item, or
 the current alignment setting.  The current alignment setting can
 be 1, 2, 4, or 8 bytes.  The default initial setting is 8 bytes
 (unless a compiler option specifies otherwise).  By reducing the
 alignment setting, you can pack variables closer together in
 memory.

 The PACK directive lets you control the packing of derived-type or
 record structure items inside your program by overriding the
 current memory alignment setting.

 For example, if CDEC$ PACK:1 is specified, all variables begin at
 the next available byte, whether odd or even.  Although this
 slightly increases access time, no memory space is wasted.  If
 CDEC$ PACK:4 is specified, INTEGER(1), LOGICAL(1), and all
 character variables begin at the next available byte, whether odd
 or even.  INTEGER(2) and LOGICAL(2) begin on the next even byte;
 all other variables begin on 4-byte boundaries.

 If the PACK directive is specified without a number, packing
 reverts to the compiler option setting (if any), or the default
 setting of 8.

 The directive can appear anywhere in a program before the
 derived-type definition or record structure definition.  It cannot
 appear inside a derived-type or record structure definition.

 For compatibility, !MS$PACK can be used in place of cDEC$ PACK.

 Examples:

 Consider the following:

 ! Use 4-byte packing for this derived type
 ! Note PACK is used outside of the derived-type definition
 !DEC$ PACK:4
 TYPE pair
   INTEGER a, b
 END TYPE
 ! revert to default or compiler option
 !DEC$ PACK: