d run-time switch

Properties:

Default: -d245760 (240 K)
Type: General

Comments:

Dynamic paging is used by programs such as the Compiler. By increasing the amount of memory you might be able to improve the performance of such programs. Once the amount of memory allocated for dynamic paging is exceeded, the run-time system pages any further requirements onto disk.

For example, when compiling a large COBOL program, the amount of memory for dynamic paging buffers might be exceeded due to the Compiler requiring a large amount of dictionary to store the symbol table it creates. When the dynamic paging buffer space is exhausted, the run-time system starts to page dynamic accesses to disk, which might have a performance overhead. By raising the amount of memory for dynamic buffering, paging to disk can be avoided (or at least reduced) and therefore better Compiler performance achieved.

Example:

To double the amount of memory (to 500k) the run-time system could use before paging to disk, you would set the COBSW environment variable as follows:

COBSW=-d500000