Version 2.1.5 vs Version 2.2.6

[Dirk Laurie <dpl@sun.ac.za>]

I have a calculation that needs to evaluate the psi function to 10000
digits.  In Pari-GP 2.1.5 there is no problem.  In Pari-GP 2.2.6 I get
a stack overflow, even with allocatemem(200*2^20), which is the biggest
my computer can comfortably do.  I have good reason to believe that the
reason is that 2.2.6 caches the Bernoulli numbers on the heap whereas
2.1.5 does not.  This is a clear case of a tradeoff: speed (for the case
when there may be some more calls to psi) vs memory.

Is there a way of controlling the decision, to cache or not to cache,
from a user program, or is it hard-wired into the two implementations?

Dirk