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:
“A country grows in history not only because of the heroism of its troops on the field of battle, it grows also when it turns to justice and to right for the conservation of its interests.”
—Aristide Briand (1862–1932)
“For a transitory enchanted moment man must have held his breath in the presence of this continent, compelled into an aesthetic contemplation he neither understood nor desired, face to face for the last time in history with something commensurate to his capacity for wonder.”
—F. Scott Fitzgerald (1896–1940)
“In the history of the human mind, these glowing and ruddy fables precede the noonday thoughts of men, as Aurora the sun’s rays. The matutine intellect of the poet, keeping in advance of the glare of philosophy, always dwells in this auroral atmosphere.”
—Henry David Thoreau (1817–1862)