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:
“As History stands, it is a sort of Chinese Play, without end and without lesson.”
—Henry Brooks Adams (1838–1918)
“All history becomes subjective; in other words there is properly no history, only biography.”
—Ralph Waldo Emerson (1803–1882)
“When the history of this period is written, [William Jennings] Bryan will stand out as one of the most remarkable men of his generation and one of the biggest political men of our country.”
—William Howard Taft (1857–1930)