# GLKMatrixStackCreate(_:) Allocates and returns a new matrix stack. ``` func GLKMatrixStackCreate(_ alloc: CFAllocator?) -> Unmanaged? ``` ## Parameters `alloc` The allocator to use to allocate the matrix stack. ## Return Value A new matrix stack, or `NULL` if an error occurred. ## Discussion A matrix stack is a Core Foundation type. Ownership follows [The Create Rule](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029) in [Memory Management Programming Guide for Core Foundation](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/CFMemoryMgmt.html#//apple_ref/doc/uid/10000127i). A matrix stack is initialized with a single identity matrix on the top of the stack. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)