FORTRAN Reference Manual

Compiler Directives
FORTRAN Reference Manual—528615-001
10-20
Using ENV COMMON
If you bind FORTRAN modules with modules created by other compilers, all the
modules that you bind together must specify or default to ENV COMMON, ENV
NEUTRAL (TAL routines only), ENV EMBEDDED (Pascal routines only), or ENV
LIBSPACE (Pascal routines only). For more information, see the Binder Manual.
•
Because the library routines in the common environment use extended addresses
for all data references, you might notice a small performance degradation when
you run your program. The actual performance degradation depends on the
percentage of time your program spends executing its own code, compared to the
time it spends executing run-time library code.
•
FORTRAN programs can open unit connections only to the standard input and
standard output files. Although a FORTRAN program cannot open a unit
connection to the standard log file, messages written by FORTRAN PAUSE
statements, STOP statements, and diagnostic messages from run-time routines
are written to the standard log file.
I/O operations to unit 5 and unit 6 might be processed as they are in C-series
systems or might use file sharing routines that apply to the standard files,
depending on the values of the file’s attributes. For more information about sharing
standard files, see the OPEN Statement on page 7-70 and Using ENV COMMON
on page 13-26.
Control blocks and memory buffers are larger than and are located in different
locations than programs compiled with ENV OLD. If your program depends on the
location of control blocks and buffers, you will need to change your program. You
should consider changing your program such that it is not dependent on the size or
location of control blocks and memory buffers.
•
The size or contents of the following buffers are different depending on whether
you specify ENV OLD or ENV COMMON:
°
The array returned in the SOURCE specifier of a READ statement that reads
from $RECEIVE
°
The CPLIST parameter to a CHECKPOINT statement and to Saved Message
Utility (SMU) routines
•
You cannot use the FORTRANCOMPLETION or FORTRANSPOOLSTART
routines. Use the FORTRAN_COMPLETION_ routine instead of
FORTRANCOMPLETION. Use the FORTRAN_SPOOL_OPEN_ routine instead of
the combination of the FORTRANSPOOLSTART routine and the OPEN statement
that precedes it. For more information, see Section 15, Utility Routines.
•
Run-time diagnostic messages have a different format. If you have a program that
depends on the format of run-time diagnostic messages reported by FORTRAN,
you must change the program.