Access Control Facility

What Does Access Control Facility Mean?

Access Control Facility 2 (ACF2) is mainframe security software distributed by Computer Associates. It is used to protect a mainframe and its resources. The software prevents the deliberate or accidental modification, deletion, corruption, or viral infection of important files and data through extensive security measures like:

  • Access control
  • Permission requirements
  • Extensive logging of activities

The system status is monitored continuously and completely, and any access attempt is logged so it helps to identify potential intruders, and allows for the identification and analysis of changes and trends in the use of the system.

Techopedia Explains Access Control Facility

Access Control Facility was originally developed by Barry Schrager, Scott Krueger and Eberhard Klemens in 1978 at London Life Insurance based in London, Ontario. The discretionary access control system was developed for the VSE, MVS, and VM operating systems. It was originally developed as a response to IBM’s RACF product developed in 1976 as an answer to the 1974 SHARE Security and Data Management project.

The North American marketing rights for the software were acquired by Cambridge Systems, who then added the "2" to the ACF name in order to differentiate it from the prototype and from the competition’s ACF/VTAM (IBM).

ACF2 has five different operation modes:

  • Quiet Mode – Only data set rules are disabled.
  • Rule Mode – Individual access rules are defined.
  • Log Mode – Access is permitted but still logged.
  • Abort Mode – This is the default mode where ACF2 bars access, logs, and issues messages.
  • Warn Mode – Access is allowed but issues warnings.

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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…