How to Link COBOL & C Together on z/OS
A highly secure enterprise operating system developed by IBM, z/OS powers large mainframe computers and provides an integrated environment for developing applications in various programming languages. You can use the interlanguage communication -- or ILC -- functionality built into z/OS to seamlessly link COBOL and C programs, as the operating system offers native support for this feature. You can call C routines from COBOL or call COBOL routines from C, or a combination of both, in much the same manner in which you would call local routines in each language.
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Instructions
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Link your C program to call your COBOL program by declaring your C and COBOL functions as follows:
Declare a function in C that passes an integer value (i) to COBOL:
void CBLRTN(int );
CBLRTN(i);Use the value “I” from the C program in your COBOL program:
01 I PIC S9(9) BINARY.
PROCEDURE DIVISION USING BY VALUE I. -
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Link your COBOL program to your C program by having the COBOL program call a C function and pass it a value, as follows:
Call the C subroutine “CFUNC” from COBOL, passing the value “I”:
01 I PIC S9(9) BINARY.
CALL "CFUNC" USING BY VALUE I.Declare the function in C:
void CFUNC(int i) {
return i;
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Declare a “pragma_linkage” at the top of your C program to explicitly declare a linkage to COBOL, which is required by some compilers. The syntax for the pragma linkage is:
“#pragma linkage(function, COBOL)”.You declare the pragma linkage and create a C function to pass a value to COBOL as follows:
#pragma linkage(CBLRTN,COBOL)
void CBLRTN(int i);
CBLRTN(i);You then use the passed variable in your COBOL program as follows:
01 I PIC S9(9) USAGE IS BINARY
PROCEDURE DIVISION USING I. -
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Declare a “pragma linkage” at the top of your C program to explicitly link the COBOL program to C. This is required by some compilers. The pragma linkage is always done in the C program, even when the COBOL program is passing the value to the C program.
You declare the variable in the COBOL program and call the C function as follows:
01 I PIC S9(9) USAGE IS BINARY
CALL 'CFUNC' USING BY CONTENT I.You then declare the pragma linkage to COBOL and define the function in C as follows:
#pragma linkage(CFUNC,COBOL)
void CFUNC(int p1) {
}
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