History
Dynamic loading was a common technique for IBM/360 Operating systems (1960s to, the - still extant - Z/Architecture), particularly for I/O subroutines, and for COBOL and PL/1 runtime libraries. As far as the application programmer is concerned, the loading is largely transparent, since it is mostly handled by the operating system (or its I/O subsystem). The main advantages are:
- Fixes (patches) to the subsystems fixed all programs at once, without the need to relink them
- Libraries could be protected from unauthorized modification
IBM's strategic transaction processing system, CICS (1970s onwards) uses dynamic loading extensively both for its kernel and for normal application program loading. Corrections to application programs could be made offline and new copies of changed programs loaded dynamically without needing to restart CICS (that can, and frequently does, run 24/7).
Read more about this topic: Dynamic Loading
Famous quotes containing the word history:
“There are two great unknown forces to-day, electricity and woman, but men can reckon much better on electricity than they can on woman.”
—Josephine K. Henry, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 4, ch. 15, by Susan B. Anthony and Ida Husted Harper (1902)
“I am not a literary man.... I am a man of science, and I am interested in that branch of Anthropology which deals with the history of human speech.”
—J.A.H. (James Augustus Henry)
“While the Republic has already acquired a history world-wide, America is still unsettled and unexplored. Like the English in New Holland, we live only on the shores of a continent even yet, and hardly know where the rivers come from which float our navy.”
—Henry David Thoreau (1817–1862)