Creating a unique identification for each stack in partitions of a host data computer such that a plurality of partitions may share a single adapter card during an Input/Output operation wherein the adapter card is exchanging data between the host and a Local Area Network. The adapter card includes a unique identifier pool for maintaining values of unique identifiers which are available for identifying the stacks. A deleted unique identifier for a stack may be reused by newly created stacks and may be reassigned to a recreated stack, if still available, when the stack had previously been deleted by the operating system, but is then recreated.