Comment by masklinn

> Some old IBM environments initialized fresh allocations to 0xDEADBEEF, which had the advantage that the result you got from using such memory would (usually) be obviously incorrect.

On BSDs, malloc.conf can still be configured to do that: on OpenBSD, junking (fills allocations with 0xdb and deallocations with 0xdf) is enabled by default on small allocations, "J" will enable it for all allocations. On FreeBSD, "J" will initialise all allocations with 0xa5 and deallocations with 0x5a.