How do I allocate RAM?

Question

For a project, I want to incrementally load the RAM of my VxWorks 7 system to test its performance under this stress. How can I do that?

I have tried a c-Script :

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void memoryIntensiveFunction() {
    size_t size = 100 * 1024 * 1024;
    char *largeMemoryBlock = (char *)malloc(size);

    if (largeMemoryBlock == NULL) {
        perror("Speicherzuweisung fehlgeschlagen");
        return;
    }

    
    for (size_t i = 0; i < size; i++) {
        largeMemoryBlock[i] = (char)(i % 256);
        if (i % (1024 * 1024) == 0) { // Jedes MB einmal lesen
            volatile char temp = largeMemoryBlock[i];
        }
    }

    sleep(1800);

    
}

int main() {
    memoryIntensiveFunction();
    return 0;
}

used:memset(); malloc(). But there is no memory allocated. Atleast memShow does not show any difference. I am struggling a bit with understanding all the specific memory terms.