The application's compiler generates DLL files from your source code. In the Windows environment, DLL code is controlled by the operating system. Once a DLL has been loaded, it is locked to the loading process, in this case CICS, and no other process can overwrite the DLL file.
When you modify existing code you need to use the procedure described below to replace an existing DLL file with the new file that you compile. To configure and load a replacement DLL file:
See the figure below for an example.
The transaction replaces any existing DLLs that your application uses with the DLLs in the staging directory. For example, to load a new version of MYPROG.DLL, you would use the following CPMT CICS transaction:
CPMT NE MYPROG
Use this process only for updating programs that are currently in use by CICS. For new programs, you must copy or compile your new program directly into the appropriate production folder.