The Server, MVS Native component supports access to DLLs.
On OS/390, the two calling conventions supported by PlatformFunction are 'c' and 'mvs'. 'c' implies that you use standard C conventions where int, float, and other values are stored directly in the parameter list and not at one level of indirection. 'mvs' implies that you use the standard 370 calling conventions where all parameters are stored in the parameter list.
When the called function is in a DLL, you specify library: '<DLL name>'. Thus, to call a DLL in an application to be run on OS/390, you might specify the following when defining the function:
function := PlatformFunction callingConvention: 'c' function: '' library: 'dllname.dll' ...
If you specify <DLL name> but the system cannot find the DLL, then the system will attempt to locate a load module.
When the called function is not in a DLL, you specify library: ''. ('' is an empty string.)
When the called function is bound with the VM load module and in the primitive table, you specify library: nil when defining a platform function.