Extend Peak RSS documentation.

Author: fniephaus

docs/reference-manual/native-image/BuildOutput.md

@@ -257,7 +257,10 @@ Increase the amount of available memory to reduce the time to build the native b
 #### <a name="glossary-peak-rss"></a>Peak RSS
 Peak [resident set size](https://en.wikipedia.org/wiki/Resident_set_size) as reported by the operating system.
 This value indicates the maximum amount of memory consumed by the build process.
-If the [GC statistics](#glossary-garbage-collection) do not show any problems, the amount of available memory of the system can be reduced to a value closer to the peak RSS.
+By default, the process will consume at least 1GB and up to 14GB of memory, but not more than what is available according to the operating system.
+If builds are slow, consider freeing up memory, for example, by closing applications that you do not need.
+To overwrite the default initial and max heap settings of the builder, use `-J-Xms` and `-J-Xmx` respectively (for example `-J-Xmx4g` for a max heap of 4GB).
+If the [GC statistics](#glossary-garbage-collection) do not show any problems, the amount of available memory of the system can be reduced to a value closer to the peak RSS to lower operational costs.
 
 #### <a name="glossary-cpu-load"></a>CPU load
 The CPU time used by the process divided by the total process time.