FORTRAN Reference Manual

Memory Organization
FORTRAN Reference Manual—528615-001
12-6
Storage Areas
Table 12-2. Compiler Directives That Control Data Allocation (page 1 of 2)
Effect
Directive ENV OLD ENV COMMON
DATAPAGES Specifies how many pages to
allocate for data storage in the
user data segment (Default:
Compiler estimates)
Always uses 64
EXTENDCOMMON Allocate one pointer for each
common block. (Default: allocate
one pointer for each variable
referenced in a common block)
Same as ENV OLD
EXTENDEDREF Generates code that uses
doubleword addresses for
parameters to subprograms.
(Default: use word addresses)
Same as ENV OLD
HIGHBUFFER n Allocate n-byte #HIGHBUF in
upper memory (Default: no
#HIGHBUF)
Allocate n-byte #CRE_HEAP
in upper memory (Default:
allocate 1,024-byte
#CRE_HEAP in upper
memory)
HIGHCOMMON blks Allocate all or specified common
blocks in high memory. If blks not
specified, allocate all common
blocks in high memory. See also
LARGECOMMON directive in
Section 10, Compiler Directives
.
(Default: allocate common blocks
in low memory or extended
memory according to
LARGECOMMON directives)
Same as ENV OLD
HIGHCONTROL Allocate #RUCB, #FLUB, #PUCB
and FCBs in high memory
(Default: allocate blocks in low
memory)
Allocate #MCB and FCBs in
high memory (Default: allocate
#MCB and FCBs in low
memory)
LARGECOMMON
blks
Allocate all or specified common
blocks in extended memory
(Default: Allocate common
blocks in low memory or high
memory according to
HIGHCOMMON directives)
Same as ENV OLD
LARGEDATA items If items is a constant, allocate
all local data with length greater
than or equal to items, in
extended memory. If items is
not a constant, allocate items in
extended memory
Same as ENV OLD