I don't know that a "lakh" of data is! I will say that once Perl gains a "lakh" or kilobyte or whatever from the O/S, it will never give it back. Perl will and can reuse this memory for its own purposes. The virtual memory "footprint" of a Perl process never gets smaller.

One of the powers of Perl is that it does the memory management for you! So in general you have no worries! Forget it (or until you get into advanced applications).

The O/S will free all memory used by an application when it ends. That is true in Java, C, Perl, etc. There is some very complex stuff about memory management, but if you are dealing with "lakh"'s I don't think you have to worry.

Update: don't worry: Make some hash and when your program ends that memory will be freed.