This sets a variable in op/numconvert.t.
+=item * PERL_TEST_MEMORY
+
+Setting this variable includes the tests in F<t/bigmem/>. This should
+be set to the number of gigabytes of memory available for testing,
+eg. C<PERL_TEST_MEMORY=4> indicates that tests that require 4GiB of
+available memory can be run safely.
+
=back
See also the documentation for the Test and Test::Harness modules, for