How big is a plugin's parameter buffer?

32K bytes. That hasn't changed since plugins were introduced.
I'm playing with the MAPM API and running into a 16K limit somewhere. This is OK ...
v:\> echo %@fact[5015] | wc
  Lines   Words   Chars
      1       1   16384
And the next one (5016) makes TCC disappear. f_FACT finishes off like this, where psz in the plugin's parameter buffer.
       m_apm_factorial(f, n);
       CHAR *szResult = (CHAR*) AllocMem(32768);
       m_apm_to_integer_string(szResult, f);
       ASCIIToUnicode(szResult, psz, 32767);