FORTRAN Reference Manual

Memory Organization
FORTRAN Reference Manual—528615-001
12-3
Data Space
defined in the memory stack. All local data in your program is referenced relative to the
L register except the dummy arguments to statement functions, which are referenced
relative to the S register.
Word-addressable and byte-addressable data can be stored in the memory stack area.
Figure 12-1. User Data Segment for ENV OLD
Space for calls to additional subroutines
Local variables named in DATA or SAVE
statements and not in LARGEDATA
Common blocks not named in
HIGHCOMMON or LARGECOMMON
Control Blocks and Run-Time Tables
(#RUCB, #FLUT, #PUCB, FCBs ...)
if program does not specify HIGHCONTROL
COMMON#POINTERS
if program references data in COMMON blocks
allocated in the User Data Segment
#G0
G[65535]
G[32768]
S Reg
L Reg
G[0]
Upper
Memory
Global
Data
Dynamic
Date
Stack for
Local and
Sublocal
Data
Lower
Memory
VST1201.vsd
Common blocks allocated by
HIGHCOMMON directive
Control Blocks and Run-Time Tables
(#RUCB, #FLUT, #PUCB, FCBs ...)
if program specifies HIGHCONTROL
Local and sublocal data for active subroutines
LOWBUFFER
Space allocated in HIGHBUFFER
directive