Unix Version 7 - man page for lock (v7 section 2)

LOCK(2) 			       System Calls Manual				  LOCK(2)

NAME
       lock - lock a process in primary memory

SYNOPSIS
       lock(flag)

DESCRIPTION
       If  the	flag  argument	is  non-zero, the process executing this call will not be swapped
       except if it is required to grow.  If the argument is zero, the process is unlocked.  This
       call may only be executed by the super-user.

BUGS
       Locked  processes  interfere with the compaction of primary memory and can cause deadlock.
       This system call is not considered a permanent part of the system.

ASSEMBLER
       (lock = 53.)
       sys lock; flag

					      local					  LOCK(2)