I don't know a lot about Micro-Focus COBOL (I do mainframe programing in a MVS environment). So I don't know what utilities might be available.
The only think I can think of is to use some sort of ACCEPT statment (whatever it is in C) at the beginning of the C program, where you get the current time. Then start computing the elapsed time at certain points within the C program. If the elapsed time goes beyond your time limit, code the C program to immediatly return to the COBOL program. Have it pass some sort of return code so that your COBOL program knows that the time limit has passed (in case you want to issue an error or warning message).
I don't know if this helps, but good luck. Nina Too