initializing a structure array using memset

gcc 4.4.4 c89

I have the following structure.

struct device_sys
{
    char device[STRING_SIZE];
    int id;
    char category;
};

int main(void)
{
    struct device_sys dev_sys[NUM_DEVICES];

    memset(dev_sys, 0, (size_t)NUM_DEVICES * sizeof(dev_sys));

    return 0; 
}

I get a stack dump when I call memset. Is this not the correct way to initialize an structure array?