Syntax for Linkage in C++
You can create linkages between C++ and other languages by using
linkage specifications with the following syntax, where linkage specifies
the linkage associated with the function. If z/OS® XL C++ does not recognize
the linkage type, it uses C linkage.
extern "linkage" { [declaration-list] }
extern "linkage" declaration
declaration-list:
declaration
declaration-list declaration