In a thin client environment, you can call subroutines in DLLs on the display host (client), as well as on the application host, when the application host is a Windows server. DLL calls to the display host involve some special considerations. Calling DLLs on the Windows application host uses the COBOL syntax and configuration variables described in A Guide to Interoperating with ACUCOBOL-GT. However, DLLs that are called on the server side and that interact with the user interface may be of limited use to thin client applications.