The AIX documentation says:
http://publib.boulder.ibm.com/infocenter/tivihelp/v2r1/index.jsp?topic=/com.ibm.itame3.doc_5.1/am51_perftune113.htm
"""It is a good idea to unset the LDR_CNTRL environment variable, so that it does not unintentionally affect other processes."""

I think people may be more interested in setting permanently the maximum memory that can be allocated by python rather than using an environment variable that may be lost and which impacts all the applications.

Another way to increase the memory available for an application is to use the ldedit command on the python executable:

ldedit -b maxdata:0x20000000 ./python

That may be easier than passing it directly to the linker.

Concerning large pages, I found that in an IBM documentation:
"""
Users are advised to be cautious in their use of the environment
variable to specify large page usage. Performance tests have shown there
can be a significant performance loss in environments where a number of
shell scripts or small, short running applications are invoked. One
example saw a shell script's execution time increase over 10 times when
the large page environment variable was specified. Customers are advised
to only set the large page environment variable around specific
applications which can benefit from large page usage.
"""
Also large pages must be activated on the system by root. This does not seem to be available by default according to the doc.