Before you can call a
C or C++ function from assembler, you must
establish a suitable environment. To establish the environment, do
one of the following:
- Call the assembler program from within the C or C++ program
(from main() or another function). Since the assembler
call is from within the C or C++ program, the environment has already
been established. It is often simplest to call the assembler using
OS linkage conventions.
Note: In this , "OS linkages" and
"OS linkage" conventions refer to the following group of specifications:
OS, OS_UPSTACK, OS_DOWNSTACK, OS_NOSTACK, OS31_NOSTACK and REFERENCE.
"OS" is used in syntax diagrams and examples as a representative specification.
These specifications use different stack conventions. For more information
on these specifications, see
Using Linkage Specifications in C or C++.
- Use preinitialization to set up the z/OS® Language Environment®. See Retaining the C environment using preinitialization for
information.
- Use the Language Environment CEEENTRY prolog macro with MAIN=YES
specified so that z/OS Language Environment is initialized.
Once you are in the assembler program, you can call other C or
C++ programs
from the assembler.