Preparing C programs in IBM i
IBM MQ for IBM i supports messages up to 100 MB in size. Application programs written in ILE C, supporting IBM MQ messages greater than 16 MB, need to use the Teraspace compiler option to allocate sufficient memory for these messages.
For more information about the C compiler options, see the WebSphere Development Studio ILE C/C++ Programmer's Guide.
To compile a C module, we can use the IBM i command,
CRTCMOD. Make sure that the library containing the include files (QMQM) is in the library list when you compile.
You must then bind the output of the compiler with the service program using the CRTPGM command.
An example of the command for a nonthreaded environment is:
Table 1. Example of CRTPGM in the nonthreaded environment
| Command |
Program/exit type |
CRTPGM PGM( pgmname ) MODULE( pgmname )
BNDSRVPGM(QMQM/LIBMQM)
|
Server or client for C |
|
where pgmname is the name of your program.
An example of the command for a threaded environment is:
Table 2. Example of CRTPGM in the threaded environment
| Command |
Program/exit type |
CRTPGM PGM( pgmname ) MODULE( pgmname )
BNDSRVPGM(QMQM/LIBMQM_R)
|
Server or client for C |
|
where pgmname is the name of your program.
The following tables list the libraries that are needed when preparing C programs on IBM i in a non-threaded environment and threaded environment.
Table 3. Non-threaded environment
| Library file |
Program/exit type |
| LIBMQM |
Server for C |
| LIBMQIC & LIBMQM |
Client for C |
Table 4. Threaded environment
| Library file |
Program/exit type |
| LIBMQM_R |
Server for C |
| LIBMQIC_R & LIBMQM_R |
Client for C |