We are updating zOS including UA96477 . There is HOLDDATA for potential impacts of other products that run on zOS. Additional Information: ACTION: Software must no longer reference the IHAPSA field PSASTAK. With this PTF, PSASTAK is no longer the beginning of the normal FRR stack. PSACSTK is an existing pointer to the beginning of the normal FRR stack. Software that references PSASTAK must be converted to use PSACSTK as the pointer to the normal FRR stack.