DOS Fn 49H: Free Allocated Memory Block
Expects: AH 49H
ES segment address (paragraph) of allocated memory to release
Returns: AX error code if CF is set to CY
Info: Deallocates (frees) the block of memory starting at ES:0000.
This block will become available for other system resources.
DOS prevents a process from freeing blocks of memory that were
allocated by another process (the PID▲ of the owner is saved
in the MCB). The undocumented DOS Fn 50H lets you become the
"current process" and thus free blocks you don't really own.
It is recommended that a TSR program free its environment block
during installation (that is, if it won't need it again!). This
allows the next program to reuse that block.
See Also: Memory Control Functions
Memory Control Block