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:
“The whole history of civilisation is strewn with creeds and institutions which were invaluable at first, and deadly afterwards.”
—Walter Bagehot (1826–1877)
“What we call National-Socialism is the poisonous perversion of ideas which have a long history in German intellectual life.”
—Thomas Mann (1875–1955)
“We said that the history of mankind depicts man; in the same way one can maintain that the history of science is science itself.”
—Johann Wolfgang Von Goethe (1749–1832)