A computer system defines a list structure on the shared medium wherein the list structure has multiple lists; and provides a list which is allocated to a single queue manager in which message entries are located which belong to multiple shared temporary dynamic queues (STDQs) created by the single queue manager, wherein the message entries are located by reference to a key which determines a message entry's position in the list, the list including: a list header which can be partitioned for multiple current STDQs by assignment of key ranges to message entries belonging each current STDQ; and a list control entry which holds information about the assignment of key ranges to the multiple current STDQs and shares the information with other queue managers using the STDQs, wherein the list control entry is updated by the single queue manager when an STDQ is created or deleted.