Compiling and linking with z/OS UNIX System Services using c89

The following c89 utility options can be specified:

IBMCPP must always be specified.
The c89 utility assumes _OPEN_SYS and includes all of the z/OS UNIX System Services MVS™ functions supported by C/370™. However, _OPEN_SOCKETS must be specified if z/OS UNIX System Services MVS sockets are being used by the application program.
```
   -D IBMCPP
   -D _OPEN_SOCKETS
```
Notes:
1. When you compile and link-edit your application program using the c89 utility with z/OS UNIX System Services sockets and TCP/IP Version 3 Release 1 for X Window System, you must include the z/OS UNIX System Services socket library before the X Window System include files:
```
   -l“//‘
sys1.SFOMHDRS’”
   -l“//‘SEZACMAC’”
 
   -l“//‘SEZAROE1’”
```
2. The flag for the prelinker libraries, -l, is a dash followed by the lowercase letter L.
If the Athena Toolkit functions are required, then also specify:
```
   -l“//‘SEZAROE2’”
```
If the Motif Toolkit functions are required, then also specify:
```
   -l“//‘SEZAROE3’”
```

To run your program under TSO, enter the following line:

   CALL ‘USER.MYPROG.LOAD(PROGRAM1)’ ‘POSIX(ON)’

This loads the run-time library from cee.v1r3m0.SCEERUN. To use the z/OS UNIX System Services MVS C/370 functions, you must either specify the run-time option:

   POSIX(ON)

or include the following statement in your C source program:

   #pragma runopts(POSIX(ON))