https://www.ibm.com/docs/en/ims/15.4.0?topic=unauth-apaub-rsncode-output-block
IMS 15.4 - System programming APIs - APAUB_RsnCode for UNAUTH output block
You can use this table to search for APAUB_RsnCode values for UNAUTH request return and reason codes. Each code is accompanied by an explanation of the code.
system programming