1. A method of executing instruction packets, each packet having a plurality of instructions, in a pipeline comprising at least first and second instruction fetch stages, a pre-decode stage, an instruction dispatch stage, first and second decoding stages, an execution stage and a write-back stage wherein the method comprises: in said first instruction fetch stage, determining the number of outstanding instructions still to be issued for execution and for initializing a packet request depending on said determination; in said second instruction fetch stage, sending said request to a memory in which said packets are stored; in said pre-decode stage, identifying from a fetched packet which instructions in said fetched packet shall be issued by extracting a set of option bits encoded in a first one of said plurality of instructions of said fetched packet, wherein the set of option bits is arithmetically added to determine a number of instructions to be issued as an issue group; and in said dispatch stage, dispatching the identified instructions for execution and reducing the number of outstanding instructions still to be issued based on the number of instructions in the issue group.