You can take advantage of existing i5/OS™ programs (*PGM objects) when you create your i5/OS PASE applications. In addition, you can use the systemCL() function to run the CL CALL command.
This method provides for faster processing than the systemCL() runtime function, but it does not perform automatic conversion of character string arguments (unless you specify PGMCALL_ASCII_STRINGS), and it does not give you the capability of calling the program in a different job.