FORTRAN Reference Manual

Compiler Directives
FORTRAN Reference Manual—528615-001
10-18
ENV Compiler Directive
ENV Compiler Directive
The ENV directive determines whether your program uses the C-series or D-series
FORTRAN run-time library.
The default value is ENV OLD.
OLD
specifies that this program use the C-series FORTRAN run-time library.
COMMON
specifies that this000 program use the D-series FORTRAN run-time library.
If you specify ENV OLD, FORTRAN:
•
Generates an object file that contains C-series data blocks that are compatible with
the C20 release of the FORTRAN compiler.
•
Processes all calls to its run-time environment using FORTRAN run-time library
routines and subsequent calls to Guardian system procedures.
If you specify ENV COMMON, FORTRAN:
•
Generates an object file that contains D-series data blocks that are defined by the
Common Run-Time Environment (CRE).
•
Processes calls to its run-time environment using FORTRAN run-time library
routines, and subsequent calls to CRE routines and Guardian system procedures.
•
Depends on the CRE to:
°
Monitor the backup process of a NonStop process pair
°
Handle traps
°
Provide the math functions required by FORTRAN programs
°
Optionally perform I/O operations for unit 5 and unit 6.
Using ENV COMMON
FORTRAN programs that specify ENV COMMON gain the following benefits:
•
You can mix object modules compiled by the C, COBOL85, FORTRAN, Pascal,
and TAL compilers more easily. There are restrictions on the operations that each
of the language modules can perform, but fewer than when you combine programs
that do not specify ENV COMMON.
ENV
OLD
COMMON
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