The CANCEL verb is only used after you have finished using a dynamicly CALLed sub-program.  The dynamic call will LOAD the sub-program into memory then execute it.  
It will remain in memory until you STOP RUN or tell the system to remove it by CANCEL Dynamic-name.
If you are short on memory or the module is very large and you now need the memory for something else, such as a large SORT, then CANCEL it.  Otherwise, CANCEL is of no practical use today with very large memory systems.

Thanks,

MSReddy