1. A computer program product embodied in a computer readable memory for allowing portions of programs to be executed on a System z Integrated Information Processor (zIIP), the computer program product comprising programming instructions for: implementing a first mode of operation in response to detecting a first service call at a beginning of eligible code that is executable on said zIIP processor, wherein said first mode of operation comprises a service request block mode of operation; and terminating said first mode of operation in response to detecting a second service call at an end of said eligible code that is executable on said zIIP processor.