Overview of the dynamic allocation program

The dynamic allocation (DYNALLOC) sample application program makes available to the CICS® terminal operator most of the functions of DYNALLOC (SVC 99).

The DYNALLOC functions are described in z/OS MVS Programming: Authorized Assembler Services Reference (Volume 1). Functions that require authorized program facility (APF) authorization are not supported.

The application consists of one command-level assembler language program, DFH99, which is started by the transaction ADYN. The source code is provided in CICSTS55.CICS.SDFHSAMP.

Using DYNALLOC functions, the terminal operator can dynamically allocate or deallocate any data set that CICS opens and closes; for example, extrapartition transient data sets, journals, or dump and trace data sets.

Do not use the dynamic allocation program to allocate and deallocate data sets that are to be associated with files managed by file control; instead, use the dynamic allocation and deallocation facility that is part of CICS. If a file has not been allocated as part of CICS startup, CICS dynamic allocation occurs immediately before the file is opened, if sufficient information is in the resource definition for the file. The information needed is the data set name and disposition of the file. This information can be set by the CEMT SET FILE main terminal transaction, described in CEMT SET FILE, or the EXEC CICS INQUIRE FILE and EXEC CICS SET FILE commands, which provide additional inquiry and control facilities, and which are described in SET FILE.

To use the dynamic allocation sample program effectively, the terminal operator requires an understanding of the MVS job control language, or TSO ALLOCATE and FREE commands. For more information, including the error and reason codes returned by the DYNALLOC function, see z/OS MVS Programming: Authorized Assembler Services Reference (Volume 1).

The sample program uses a 3270 display screen terminal, and adjusts its formatting to suit the screen size. BMS is not required. The program is designed so that the installation can easily modify the functions supported to suit installation standards.