The exit routine is reloaded automatically from the module library SYSLNK.TCP-IP-AP.nnn or SKMLNK.TCP-IP-AP.nnn (on x86 systems) when the FTP client program or connectionspecific server task is started. To avoid "UNRESOLVED EXTERNAL REFERENCES" problems here, the specified libraries must always contain a module with the entry YAPFEXIT.
The module libraries mentioned are therefore supplied with a dummy routine, which is contained in the LMS element EXITFTP. This routine does not perform any conversion rather logs the transferred data in standard output and otherwise returns it unchanged. You can use the source text for this routine, which can be found in the S element EXITFTP.C in the SYSSRC.TCP-IP-AP.nnn library, as the starting point for your own routines. The header file required here can be found in the SYSLIB.TCP-IP-AP.nnn library. If you want to create the routine in Assembler, you should use the macro YAPFX. Note that the routine is called in accordance with C conventions.
If you are using your own routine, you should note that only one module with the entry point YAPFEXIT may exist in the module library as otherwise the wrong module may be loaded. In particular, therefore, you should remove the module element EXITFTP supplied.
Because the entry point YAPFEXIT is not selected by default, you have to activate it using an FTP server option or a command.