Consider the Interactive System Productivity Facility (ISPF) program product an extension of the MVS™ Time Sharing Option (TSO) host system on which it runs. ISPF services complement those of the host system to provide interactive processing. ISPF is similar to a control program or access method in that it provides services to dialogs (applications) during their execution. The types of services provided by ISPF are:

• Display services
• File-tailoring services
• Variable services
• Table services
• Miscellaneous services
• Dialog test facility, including:
  • Setting breakpoints
  • Tracing usage of dialog services and dialog variables
  • Browsing trace output in the ISPF log data set
  • Examining and updating ISPF tables
  • Interactively invoking most dialog services.