Currently we use a helper function my_disclaim64 to simulate disclaim64.
The reason documented in the source code was support of (very) old AIX versions. However AIX 7.1 and higher support disclaim64 so the workaround seems to be obsolete.
See
https://www.ibm.com/docs/en/aix/7.1?topic=d-disclaim-disclaim64-subroutines
https://www.ibm.com/docs/en/aix/7.2?topic=d-disclaim-disclaim64-subroutines
The reason documented in the source code was support of (very) old AIX versions. However AIX 7.1 and higher support disclaim64 so the workaround seems to be obsolete.
See
https://www.ibm.com/docs/en/aix/7.1?topic=d-disclaim-disclaim64-subroutines
https://www.ibm.com/docs/en/aix/7.2?topic=d-disclaim-disclaim64-subroutines