Methods, software media, compilers and programming techniques are described for creating copyable stack-based closures, such as a block, for languages which allocate automatic or local variables on a stack memory structure. In one exemplary method, a data structure of the block is first written to the stack memory structure, and this may be the automatic default operation, at run-time, for the block; then, a block copy instruction, added explicitly (in one embodiment) by a programmer during creation of the block, is executed to copy the block to a heap memory structure. The block includes a function pointer that references a function which uses data in the block.