What happens if an identity change does not take place when a child is created?

Normally, the child inherits the parent's current hard and soft limits. However, a change to the child's limit causes the child's hard and soft limit to be set to the hard limit. The child's limit can be changed by the parent in the inheritance structure on spawn() or by IEFUSI. How the system honors changes made in the inheritance structure or IEFUSI will vary depending on the parent's security setting.

When the same limit is not defined in the OMVS segment, the system will honor IEFUSI even if the parent requests a change using the inheritance structure (Inhe).

After a limit has been defined for a parent identity by the security administrator, that limit is trusted before other system components only if it is higher than the MVS™ limits. When a limit is defined in the OMVS segment:

The system ignores requests by IEFUSI to change the limit in the OMVS segment if the limit in the OMVS segment is higher than the limit set in IEFUSI. The OMVS segment is in control of ASSIZE and MEMLIMIT. If the OMVS segment value is lower than IEFUSI, then IEFUSI sets hard and soft limits for both MEMLIMIT and ASSIZE. IEFUSI is in control of ASSIZE and MEMLIMIT.
If the OMVS segment is in control of ASSIZE and MEMLIMIT for the parent, the system also ignores requests by IEFUSI to change limits for child processes that were created by that identity. In this case, the child is created with the parent's current limits. If IEFUSI is in control of ASSIZE and MEMLIMIT for the parent, the child's MEMLIMIT and ASSIZE will be set by IEFUSI. In both cases, if IEFUSI is active in the system and is attempting to control limits for an OMVS address space, the inheritance structure (Inhe) is ignored for MEMLIMIT and ASSIZE.