system
Linkage convention used in C programming under the IBM C Set/2 compiler, which causes the compiler to generate object code for a function or subroutine, such that parameters are placed on the stack in right-to-left order, and the stack is cleared by the calling function when control is returned. The system linkage convention differs from the default optlink linkage convention in the preservation of register values and the handling of return values. Use of the system linkage convention is required for functions that are invoked by the operating system or Presentation Manager, such as window and dialog procedures. The system linkage convention is specified using the #pragma linkage directive.