Here's an example program in Python that stores the largest and smallest of three integer values entered by the user:
```python
# Declare variables for largest and smallest
largest = None
smallest = None
# Prompt user to enter three integers
num1 = int(input("Enter first integer: "))
num2 = int(input("Enter second integer: "))
num3 = int(input("Enter third integer: "))
# Determine largest number
if num1 >= num2 and num1 >= num3:
largest = num1
elif num2 >= num1 and num2 >= num3:
largest = num2
else:
largest = num3
# Determine smallest number
if num1 <= num2 and num1 <= num3:
smallest = num1
elif num2 <= num1 and num2 <= num3:
smallest = num2
else:
smallest = num3
# Output results
print("The largest value is", largest)
print("The smallest value is", smallest)
```
In this program, the variables `largest` and `smallest` are declared and initialized to `None`. Three additional variables `num1`, `num2`, and `num3` are declared and initialized with integer values entered by the user using the `input()` function and converted to integers using the `int()` function.
The program then uses a series of `if` and `elif` statements to determine the largest and smallest of the three numbers, based on their values. The `largest` and `smallest` variables are updated accordingly.
Finally, the program outputs the results using two `print()` statements.v