The memory dialog you describe was removed from 7.4. Let me explain why…
Prior to 7.4 the “context” memory for concurrent sessions was allocated from the Fastpath shared memory area (buffer). This accounted for much of the “memory classes” reported on this dialog such as “user”, “read-ahead” etc.
However, there were internal problems associated with allocating context from shared memory. This was enhanced at 7.4 and is now allocated from private memory allowing read-ahead operations (etc) to continue even if the Fastpath daemon suffers unplanned outage.
This is a healthy enhancement, but it renders the dialog you mention redundant. From 7.4, 100% of the shared memory area is devoted to direct-access caching so the “classes” is no longer relevant. You can get useful information by using PF9 (“parm”) from the statistics display.
I hope this helps.