The Free On-line Dictionary of Computing (19 January 2023):

Lan Manager

    Microsoft's OS/2-based network
   operating system.  Developed in conjunction with 3Com, Lan
   Manager runs as a task under OS/2.  Because of this, a file
   server may concurrently be used for other tasks, such as
   database services.  It offers good mulitasking.

   (1997-03-19)