DLLs are shared at the enclave level (as defined by Language Environment). A referenced DLL is loaded only once per enclave and only one copy of the writable static is created or maintained per DLL per enclave. Thus, one copy of a DLL serves all modules in an enclave regardless of whether the DLL is loaded implicitly or explicitly. A copy is implicit through a reference to a function or variable. A copy is explicit through a DLL load. You can access the same DLL within an enclave both implicitly and by explicit runtime services.

All accesses to a variable in a DLL in an enclave refer to the single copy of that variable. All accesses to a function in a DLL in an enclave refer to the single copy of that function.

Although only one copy of a DLL is maintained per enclave, multiple logical loads are counted and used to determine when the DLL can be deleted. For a given DLL in a given enclave, there is one logical load for each explicit dllload() or dlopen() request. DLLs that are referenced implicitly may be logically loaded at application initialization time if the application references any data exported by the DLL, or the logical load may occur during the first implicit call to a function exported by the DLL.