OPTIONS

 cDEC$ OPTIONS

 Affects data alignment and warnings about data alignment.  The
 OPTIONS directive takes the following form:

 cDEC$ OPTIONS option [option]
   ...
 cDEC$ END OPTIONS

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

   option  Is one or both of the following:

   o /WARN=[NO]ALIGNMENT

   Controls whether warnings are issued by the compiler for 
   data that is not naturally aligned.  By default, you receive
   compiler messages when misaligned data is encountered
   (/WARN=ALIGNMENT).

   o /[NO]ALIGN[=p]

   Controls whether the VSI Fortran compiler naturally aligns 
   fields in derived-type and record structures and data items 
   in common blocks for performance reasons, or whether the 
   compiler packs those fields and data items together on 
   arbitrary byte boundaries. 

   p  Is a specifier with one of the following forms:

    [class =] rule    
    (class = rule,...) 
    ALL
    NONE

    class  Is one of the following keywords:

        COMMONS    (for common blocks)
        RECORDS    (for derived-type and record structures)
        STRUCTURES (a synonym for RECORDS)

    rule   Is one of the following keywords:

           PACKED -   Packs fields in structures or data 
                      items in common blocks on arbitrary 
                      byte boundaries.

           NATURAL -  Naturally aligns fields in structures
                      and data items in common blocks on 
                      up to 64-bit boundaries (inconsistent 
                      with the FORTRAN 77 standard).

                      If you specify NATURAL, the compiler will 
                      naturally align all data in a common 
                      block, including INTEGER*8, REAL*8, and 
                      all COMPLEX data.

           STANDARD - Naturally aligns data items in common 
                      blocks on up to 32-bit boundaries (con-
                      sistent with the FORTRAN 77 standard).

                      Note that this keyword only applies to 
                      common blocks; so, you can specify 
                      /ALIGN=COMMONS=STANDARD, but you cannot 
                      specify /ALIGN=STANDARD.

    ALL    Is the same as /ALIGN, /ALIGN=NATURAL, and 
           /ALIGN=(RECORDS=NATURAL,COMMONS=NATURAL).

    NONE   Is the same as /NOALIGN, /ALIGN=PACKED, and
           /ALIGN=(RECORDS=PACKED,COMMONS=PACKED)

 cDEC$ OPTIONS (and accompanying cDEC$ END OPTIONS) directives must
 come after OPTIONS, SUBROUTINE, FUNCTION, and BLOCK DATA statements
 (if any) in the program unit, and before statement functions or the
 executable part of the program unit.

 For performance reasons, VSI Fortran always aligns local data
 items on natural boundaries.  However, EQUIVALENCE, COMMON, RECORD,
 and STRUCTURE data declaration statements can force misaligned
 data.  If /WARN=NOALIGNMENT is specified, warnings will not be
 issued if misaligned data is encountered.

                                NOTE

         Misaligned data significantly increases the time it
         takes  to  execute  a  program.   As  the number of
         misaligned fields encountered  increases,  so  does
         the  time  needed  to  complete  program execution.
         Specifying  cDEC$  OPTIONS/ALIGN  (or  the   /ALIGN
         compiler option) minimizes misaligned data.


 To request aligned, data in common blocks, specify
 /ALIGN=COMMONS=STANDARD (for data items up to 32 bits in length) or
 /ALIGN=COMMONS=NATURAL (for data items up to 64 bits in length), or
 place source data declarations within the common block in
 descending size order, so that each data field is naturally
 aligned.

 To request packed, unaligned data in a record structure, specify
 /ALIGN=RECORDS=PACKED, or consider placing source data declarations
 for the record so that the data is naturally aligned.

 The OPTIONS directive supersedes the /ALIGN compiler option.

 OPTIONS directives must be balanced and can be nested up to 100
 levels, for example:

    CDEC$ OPTIONS /ALIGN=PACKED         ! Group A
       declarations
    CDEC$ OPTIONS /ALIGN=RECO=NATU         ! Group B
       more declarations
    CDEC$ END OPTIONS                      ! End of Group B
       still more declarations
    CDEC$ END OPTIONS                   ! End of Group A

 Note that common blocks within Group B will be PACKED.  The CDEC$
 OPTION specification for Group B only applies to RECORDS, so
 COMMONS retains the previous setting (in this case, from the Group
 A specification).

 For more information on alignment and data sizes, see the HP
 Fortran for OpenVMS User Manual.