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:
“Every generation rewrites the past. In easy times history is more or less of an ornamental art, but in times of danger we are driven to the written record by a pressing need to find answers to the riddles of today.... In times of change and danger when there is a quicksand of fear under men’s reasoning, a sense of continuity with generations gone before can stretch like a lifeline across the scary present and get us past that idiot delusion of the exceptional Now that blocks good thinking.”
—John Dos Passos (1896–1970)
“Most events recorded in history are more remarkable than important, like eclipses of the sun and moon, by which all are attracted, but whose effects no one takes the trouble to calculate.”
—Henry David Thoreau (1817–1862)
“The history of all hitherto existing society is the history of class struggles.”
—Karl Marx (1818–1883)