What Are Dynamic Loading, Dynamic Linking And Overlays
Dynamic Loading: ► Routine is not loaded until it is called ► Better memory-space utilization; unused routine is never loaded. ► Useful when large amounts of code are needed to handle infrequently occurring cases. ► No special support from the operating system is required implemented through program design.Dynamic Linking: ► Linking postponed until execution time. ► Small piece of code, stub, used to locate the appropriate memory-resident library routine. ► Stub replaces itself with the address of the routine, and executes the routine. ► Operating system needed to check if routine is in processes? memory address. ► Dynamic linking is particularly useful for libraries.Overlays: ► Keep in memory only those instructions and data that are needed at any given time. ► Needed when process is larger than amount of memory allocated to it. ► Implemented by user, no special support needed from operating system, programming design of overlay structure is complex.
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