Binary createBlock(Int bsize)
bsize: The size of the block. Block sizes cannot be changed once the block is created.
Create a new, uninitialised block for binary data. Remember to use Builtins::byteLength instead of Builtins::length if you want to store Strings in these, as you may have problems with multi-byte characters otherwise.
The uninitialised contents of this block are not guaranteed to be zeroes.