ZSTD_BLOCKHEADERSIZE
static UNUSED_ATTR const size_t ZSTD_blockHeaderSize = ZSTD_BLOCKHEADERSIZE;
ZSTD_STATIC_ASSERT(ZSTD_BLOCKHEADERSIZE == 3);
{ size_t const lastBlockSize = zcs->frameEnded ? 0 : ZSTD_BLOCKHEADERSIZE;