/rpcss switch
The /rpcss switch, when specified, acts as though the enable_allocate attribute was specified on all operations of the interface. The usage of this attribute is not recommended.
midl /rpcss
This switch has no parameters.
In default mode, 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.
midl /rpcss filename.idl