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You can ask for warnings as the program approaches running out of memory
space, by calling memory_warnings. This tells malloc to
check memory usage every time it asks for more memory from the operating
system. This is a GNU extension declared in `malloc.h'.
Function: void memory_warnings (void *start, void (*warn_func) (const char *))
Call this function to request warnings for nearing exhaustion of virtual memory.
The argument start says where data space begins, in memory. The allocator compares this against the last address used and against the limit of data space, to determine the fraction of available memory in use. If you supply zero for start, then a default value is used which is right in most circumstances.
For warn_func, supply a function that malloc can call to
warn you. It is called with a string (a warning message) as argument.
Normally it ought to display the string for the user to read.
The warnings come when memory becomes 75% full, when it becomes 85% full, and when it becomes 95% full. Above 95% you get another warning each time memory usage increases.
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