Does the delete statement immediately release memory in GNU AWK?

Associative Array Memory Reclamation

AWK scripts processing massive datasets often rely on associative arrays to track state. To prevent unbounded memory growth during long-running processes, the delete statement is used to remove specific elements or clear the entire array.

While delete removes the logical association between a key and a value, the underlying memory management varies by implementation. In GNU AWK (gawk), it is unclear whether the memory occupied by deleted elements is immediately returned to the operating system or retained by the process for future allocations to optimize performance.

What is the internal behavior of gawk regarding heap memory reclamation after a large-scale delete operation? Does the implementation utilize a caching mechanism that prevents the resident set size (RSS) from decreasing even after the array is emptied?