Some conditions encountered in a program cause a program interruption. These conditions include incorrect parameters and parameter specifications, as well as exceptional results, and are known generally as program exceptions. The program status word's (PSW) program mask provide bits to control certain program exceptions. When MVS™ gives control to programs, these bits are usually off, disabling the program exceptions. However, MVS also provides the ESPIE and SPIE services to enable program exceptions and to allow a user exit routine to receive control when those exceptions occur. This chapter describes the use of ESPIE and SPIE services.