IBM Enhanced EHLLAPI (32-bit) and IBM® Standard EHLLAPI 16-bit connect on a per process basis. All threads access the same connected host session. The thread that performs the connections must also perform the disconnection.

IBM Standard EHLLAPI (32-bit) and WinHLLAPI connect on a per thread basis. Each thread must maintain its own connections. This allows a multithreaded process to maintain connections to more than one connected host session at a time. This eliminates the need for multi-process schemes when using a WinHLLAPI program to coordinate data between different hosts. It also puts the burden of connecting and disconnecting as necessary on the individual thread.