The LXRES macro supplies the service provider with a linkage index. Because the PC routine is to be available to all users, the service provider should obtain a system LX. Note that there are a limited number of system LXs available. You should either be prepared to reuse the system LX if your address space terminates and then restarts, or you should specify REUSABLE=YES on the LXRES macro. See Reassigning LXs when the LX reuse facility is enabled for more information about system LXs.