midl /rpcss
midl /rpcss filename.idl
The /rpcss switch, when specified, acts as though the enable_allocate attribute was specified on all operations of the interface. In the default mode of operation, the rpcss package is enabled only if either the procedure or interface has the enable_allocate attribute or the /rpcss switch is specified on the command line. In /osf mode, the server side stub enables the rpcss allocation package.
General MIDL Command-line Syntax, IDL, enable_allocate, /osf