Format of General Service Control Block:
Offset	Size	Description	)
 00h	DWORD	-> next GSCB (maintained internally by LSL)
 04h	DWORD	-> entry point for general service handler
 08h	WORD	command code for this general service (8000h-FFFFh)
Note:	the control block must not be altered or deallocated until the general
	  service is removed