More Work items - More Resource usage?

What about BRAM blocks when my thread uses private memory? Would the private memory allocated for one item gets reused? What happens when I use attributes like SIMD and CU? For eg:- In the case of GEMM example, doubling the SIMD attribute doubles the BRAM usage. I can understand that doubling of BRAM blocks with increasing CU attribute but why would SIMD attribute increase BRAM. Is it because of the local memory replication? Is there any attribute to set a limit for the replication of local memory?