FORTRAN Reference Manual

Memory Organization
FORTRAN Reference Manual—528615-001
12-4
Data Space
Three logical areas within the user data segment are available to a FORTRAN
subprogram while it is active:
•
COMMON, DATA, and SAVE areas, using G-plus addressing
•
Subprogram parameter (argument) area, using L-minus addressing
•
Local area, using L-plus addressing
Figure 12-2. User Data Segment for ENV COMMON
Space for calls to additional subroutines
G[65535]
G[32768]
S Reg
L Reg
G[0]
Upper
Memory
Global
Data
Dynamic
Date
Stack for
Local and
Sublocal
Data
Lower
Memory
VST1202.vsd
#CRE_HEAP
#MCB
if program specifies HIGHCONTROL
Common blocks allocated in
HIGHCOMMON directives
Local data for active subroutines
FCBs if program does not specify
HIGHCONTROL
#MCB
if program does not specify HIGHCONTROL
Local variables named in DATA or SAVE
statements and not in LARGEDATA
Common blocks not named in
HIGHCOMMON or LARGECOMMON
COMMON#POINTERS
if program references data in COMMON blocks
allocated in the User Data Segment
#CRE_GLOBALS