How can I plug-in my own memory management in Bison?

[Ashish Mahamuni]

I have got my own "my_malloc" and "my_free" methods.
I would like Bison to invoke those for memory allocation and to free the
memory.

Basically, something similar to lex, where I can specify noyyalloc,
noyyfree and provide my own definitions.

I tried #define YYMALLOC, but it did not work.

is this possible with Bison?

--Ashish