cDEC$ PSECT /common-name/ attr [,attr,...]
Lets you modify several characteristics of a common block.
Specify the name of a common block, preceded and followed by a
slash, and one of the following keywords ("attr"):
o ALIGN=val or ALIGN=keyword
Specifies alignment for the common block.
"val" must be a constant ranging from 0 through 16.
The specified number is interpreted as a power of 2. The value
of the expression is the alignment in bytes.
"keyword" is one of the following:
Keyword Equivalent to "val"
BYTE 0
WORD 1
LONG 2
QUAD 3
OCTA 4
PAGE [see note] Alpha: 16
Intel: 12
note: Range for Alpha is 0 to 16; for
Intel, 0 to 12.
The default is octaword alignment (4).
o GBL
Specifies global scope. This is the default scope.
o LCL
Specifies local scope. This keyword is opposite to GBL and
cannot appear with it.
o [NO]MULTILANGUAGE
Controls whether the compiler pads the size of overlaid psects
(program sections) to ensure compatibility when the psect is
shared by code created by other OpenVMS compilers.
When a psect generated by a Fortran common block is overlaid
with a psect consisting of a C structure, linker error messages
can occur. This is because the sizes of the psects are
inconsistent; the C structure is padded, but the Fortran common
block is not.
Specifying MULTILANGUAGE ensures that VSI Fortran follows a
consistent psect size allocation scheme that works with HP
C psects shared across multiple images. Psects shared in a
single image do not have a problem.
The default is NOMULTILANGUAGE. This is also the default
behavior of HP Fortran 77 and is sufficient for most
applications.
To specify MULTILANGUAGE for all COMMON blocks in a module, use
compiler option /ALIGN=COMMON=MULTILANGUAGE. (For more
information, see the HP Fortran for OpenVMS User Manual.)
o [NO]SHR
Determines whether the contents of a common block can be shared
by more than one process. The default is NOSHR.
o [NO]WRT
Determines whether the contents of a common block can be
modified during program execution. The default is WRT.
Global or local scope is significant for an image that has more
than one cluster. Program sections with the same name that are
from different modules in different clusters are placed in separate
clusters if local scope is in effect. They are placed in the same
cluster if global scope is in effect.
If one program unit changes one or more characteristics of a common
block, all other units that reference that common block must also
change those characteristics in the same way.
Default characteristics apply if you do not modify them with a
PSECT directive.
See the "OpenVMS Linker Utility Manual" for detailed information
about default attributes of common blocks.