Perl doesn't have "garbage collection" in the sense that it never gives memory back to the OS.

That's demonstrably not exactly true:

C:\test>perl -E"say `tasklist|find \"$$\"`; $x=chr(0); $x x= 2e6; say 
+`tasklist|find \"$$\"`; undef $x; say `tasklist|find \"$$\"`"
perl.exe                    139252 Console                    1      4
+,660 K
perl.exe                    139252 Console                    1      6
+,680 K
perl.exe                    139252 Console                    1      4
+,724 K
[download]

That shows that perl allocating a 2MB scalar and then returning that 2MB back to the OS.

On my Perl/system, the break point for the size of allocations that are released back to the system is 1040351 bytes. anything more and it is; less and it is not:

C:\test>perl -E"say `tasklist|find \"$$\"`; $x=chr(0); $x x= 1040352; 
+say `tasklist|find \"$$\"`; undef $x; say `tasklist|find \"$$\"`"
perl.exe                    129340 Console                    1      4
+,688 K
perl.exe                    129340 Console                    1      5
+,788 K
perl.exe                    129340 Console                    1      4
+,780 K

C:\test>perl -E"say `tasklist|find \"$$\"`; $x=chr(0); $x x= 1040351; 
+say `tasklist|find \"$$\"`; undef $x; say `tasklist|find \"$$\"`"
perl.exe                    241476 Console                    1      4
+,704 K
perl.exe                    241476 Console                    1      5
+,788 K
perl.exe                    241476 Console                    1      5
+,792 K
[download]

That number is a around 8k less than 1MB, so presumably it is 1MB internally but then some is used for internal management.