The Tosca Host Engine is installed by default as part of a complete Tricentis Tosca installation.
All information regarding software versions and hardware requirements for the engine can be found in the "System Requirements for Tricentis Tosca 14.2 LTS".
The file PCSHLL32.DLL needs to exist in the system and the operating system needs to know the path to this file (with the system variable PATH).
The 3270 terminal emulation needs to be initialized correctly, so that the connection to the HOST system to be tested can be established. Additional information is available from your system administrator.