Perl won't release memory back to the operating system at runtime, only on global destruction as the script terminates.
While that may be true for most practical purposes, I believe Perl simply defers to the implementation of the user-level malloc function - see for example: Memory is not released back to operating system.

Last time I looked, both Linux and Windows malloc do return "large" chunks back to the OS.

In reply to Re^2: Perl Memory problem ... by eyepopslikeamosquito
in thread Perl Memory problem ... by Sascha2018

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