Each time you call a service, your program receives either a return code and reason code or an abend code and a reason code. These codes indicate whether the service completed successfully, encountered an unusual condition, or was unable to complete successfully.

When you receive a return code that indicates a problem or an unusual condition, your program can either attempt to correct the problem or can terminate its execution. Return codes and reason codes are explained in Window services with the description of each callable service program.

When an abend occurs, the system passes control to a recovery routine, if you or your installation have provided one. A recovery routine might be able to correct the problem that caused the abend and allow your program to continue execution. If a recovery routine has been provided, it can handle the abend condition the same way it handles other abend conditions. If a recovery routine has not been provided, the system terminates execution of your program. For an explanation of the abend codes, see z/OS MVS System Codes.