diff --git a/PerfectNumbers.Core/ConcurrentFixedCapacityStack.cs b/PerfectNumbers.Core/ConcurrentFixedCapacityStack.cs
index 3efa874..dcc983e 100644
--- a/PerfectNumbers.Core/ConcurrentFixedCapacityStack.cs
+++ b/PerfectNumbers.Core/ConcurrentFixedCapacityStack.cs
@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 
 namespace PerfectNumbers.Core;
@@ -29,7 +30,11 @@ public sealed class ConcurrentFixedCapacityStack<T>(int capacity)
 	public T? Pop() => TryPop(out T? item) ? item : default;
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-	public bool TryPop(out T? item)
+	/// <summary>
+	/// Tries popping the first element from the stack. It doesn't clear the internal memory buffer from unused references.
+	/// </summary>
+	/// <returns>Returns false when the stack is empty. Returns true otherwise. If the stack was not empty, item contains the first element from the stack.
+	public bool TryPop([NotNullWhen(true)] out T? item)
 	{
 		while (true)
 		{
@@ -43,7 +48,7 @@ public sealed class ConcurrentFixedCapacityStack<T>(int capacity)
 			int next = observed - 1;
 			if (Interlocked.CompareExchange(ref _count, next, observed) == observed)
 			{
-				item = _items[next];
+				item = _items[next]!;
 				return true;
 			}
 		}
@@ -59,8 +64,7 @@ public sealed class ConcurrentFixedCapacityStack<T>(int capacity)
 			return;
 		}
 
-		Interlocked.Decrement(ref _count);
-		throw new InvalidOperationException("Stack is full.");
+		ArgumentOutOfRangeException.ThrowIfGreaterThan(next, _capacity);
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
diff --git a/PerfectNumbers.Core/FixedCapacityPools.cs b/PerfectNumbers.Core/FixedCapacityPools.cs
index 78dc992..81fbcdd 100644
--- a/PerfectNumbers.Core/FixedCapacityPools.cs
+++ b/PerfectNumbers.Core/FixedCapacityPools.cs
@@ -6,7 +6,7 @@ namespace PerfectNumbers.Core
 	{
 		[ThreadStatic]
 		private static FixedCapacityArrayPool<T>? _arrayPool;
-		internal static FixedCapacityArrayPool<T> ExclusiveArray
+		public static FixedCapacityArrayPool<T> ExclusiveArray
 		{
 
 			[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
@@ -18,7 +18,7 @@ namespace PerfectNumbers.Core
 	{
 		[ThreadStatic]
 		private static IntArrayPool? _intArrayPool;
-		internal static IntArrayPool ExclusiveIntArray
+		public static IntArrayPool ExclusiveIntArray
 		{
 
 			[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
@@ -27,7 +27,7 @@ namespace PerfectNumbers.Core
 
 		[ThreadStatic]
 		private static UlongArrayPool? _ulongArrayPool;
-		internal static UlongArrayPool ExclusiveUlongArray
+		public static UlongArrayPool ExclusiveUlongArray
 		{
 
 			[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
diff --git a/PerfectNumbers.Core/FixedCapacityStack.cs b/PerfectNumbers.Core/FixedCapacityStack.cs
index 19bc6c4..e5c0440 100644
--- a/PerfectNumbers.Core/FixedCapacityStack.cs
+++ b/PerfectNumbers.Core/FixedCapacityStack.cs
@@ -27,9 +27,16 @@ public sealed class FixedCapacityStack<T>(int capacity)
 		}
 	}
 
+	/// <summary>
+	/// Sets the no. of elements on the stack to 0. It doesn't clear the internal memory buffer from unused references.
+	/// </summary>
 	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
 	public void Clear() => Count = 0;
 
+	/// <summary>
+	/// Pops and returns the first element from the stack. It doesn't clear the internal memory buffer from unused references.
+	/// </summary>
+	/// <returns>The first element on the stack or null / default when the stack is empty.
 	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
 	public T? Pop() => Count > 0 ? _items[Count--] : default;
 
@@ -37,9 +44,10 @@ public sealed class FixedCapacityStack<T>(int capacity)
 	public void Push(T item)
 	{
 		int newCount = Count + 1;
-		if (newCount < _items.Length)
+		T[] items = _items;
+		if (newCount < items.Length)
 		{
-			_items[newCount] = item;
+			items[newCount] = item;
 			Count = newCount;
 		}
 	}