An alternative to killing and yanking stack entries is using registers in Calc. Saving stack entries in registers is like saving text in normal Emacs registers; although, like Calc's kill commands, register commands always operate on whole stack entries.
Registers in Calc are places to store stack entries for later use;
each register is indexed by a single character. To store the current
region (rounded up, of course, to include full stack entries) into a
register, use the command r s (
You will then be prompted for a register to use, the next character
you type will be the index for the register. To store the region in
register r, the full command will be r s r. With an
argument, C-u r s r, the region being copied to the
register will be deleted from the Calc buffer.
It is possible to add additional stack entries to a register. The command M-x calc-append-to-register will prompt for a register, then add the stack entries in the region to the end of the register contents. The command M-x calc-prepend-to-register will similarly prompt for a register and add the stack entries in the region to the beginning of the register contents. Both commands take C-u arguments, which will cause the region to be deleted after being added to the register.