unlimit [-h] [resource]
unlimit removes the limitation on resource or, if no resource is specified, all resource limitations.
The hard limit can be lowered to any value that is greater than or equal to the soft limit. All hard limits can be raised only by a process which has superuser authority. This behavior is identical to ulimit in the z/OS shell. If a user attempts to remove the soft limit on a resource, and their effective UID is not 0, then unlimit sets the soft limit to the current hard limit value.
limit, tcsh, ulimit
Also see setrlimit() in z/OS XL C/C++ Runtime Library Reference.