The screenshots shows that u are examining IDA's detailed stack view.

IDA gives a name  to every byte that is accessed directly in the function, any other bytes remain undefined.

Calling convention ? Give us the prologue and the epilogue of this subroutine so we can see how the stack is allocated and cleaned.
 
So if this is a stack frame of a normal application written in high level language (not malware nor written in assembly by hand) and not calling convention specific then i think we can agree that the compiler allocated more stack space than this function needs for some reason.

I dont think it is a "must" to know why the compiler did this, but thats your choice.