It allocates storage as well:

```
In [5]: backend._ffi.new("size_t *")
Out[5]: <cdata 'size_t *' owning 8 bytes>

In [6]: backend._ffi.new("int *")
Out[6]: <cdata 'int *' owning 4 bytes>

In [3]: backend._ffi.new("RSA *")
Out[3]: <cdata 'RSA *' owning 168 bytes>
```