Used only with memory_pools on:
memory_pools_limit 50 MB
If set to a non-zero value, Squid will keep at most the specified
limit of allocated (but unused) memory in memory pools. All free()
requests that exceed this limit will be handled by your malloc
library. Squid does not pre-allocate any memory, just safe-keeps
objects that otherwise would be free()d. Thus, it is safe to set
memory_pools_limit to a reasonably high value even if your
configuration will use less memory.
If set to none, Squid will keep all memory it can. That is, there
will be no limit on the total amount of memory used for safe-keeping.
To disable memory allocation optimization, do not set
memory_pools_limit to 0 or none. Set memory_pools to "off" instead.
An overhead for maintaining memory pools is not taken into account
when the limit is checked. This overhead is close to four bytes per
object kept. However, pools may actually _save_ memory because of
reduced memory thrashing in your malloc library.