Appendix B. Glossary ACID properties. The properties of a transaction: atomicity, consistency, isolation, and durability. In CICS, the ACID properties apply to a unit of work (UoW). address. The unique code assigned to each device, workstation or system connected to a network. address space. The complete range of addresses available to a program. In z/OS, an address space can range up to 16 exabytes of contiguous virtual storage addresses that the system creates for the user. An address space contains user data and programs, as well as system data and programs, some of which are common to all address spaces. See also virtual address space. addressing mode (AMODE). A program attribute that refers to the address length that is expected to be in effect when the program is entered. In z/OS, A abend. abnormal end. abnormal end. End of a task, a job, or a subsystem because of an error condition that cannot be resolved by recovery facilities while the task is performed. See also abnormal termination. abnormal termination. (1) The end of processing prior to scheduled termination. (2) A system failure or operator action that causes a job to end unsuccessfully. Synonymous with abend, abnormal end. ACB. access control block. ACCEPT. The SMP/E command used to install SYSMODs in the distribution libraries.