This text overcomes the limitations of most of the technical literature concerning JCL by providing comprehensive examples and practical guidance throughout. The text focuses on the functional, relevant topics programmers need to know to get work done in a business data processing environment. Examples start with what a programmer needs to know to test a job, then builds up to what must be done to move the job into production. This learn-by-doing approach also shows how JCL is integrated with online facilities such as TSO. A complete summary of contemporary system completion codes is featured with advice for problem resolutions and fresh coverage of condition code testing, generation data group creation and usage and more.