Advanced ACBGEN utility overview

Advanced ACBGEN utility is a replacement for the IMS™ ACBGEN utility (DFSUACB0), with enhancements. The Advanced ACBGEN utility can also replace the IMS ACBGEN utility used to generate ACB members within ACB Generation and Catalog Populate utility (DFS3UACB) jobs. It uses some of the modules provided by IMS, and replaces others. Additionally, several utilities are provided to display and audit the contents of an ACB library.

The current ACB generation process provided with IMS consists of three basic modules. Each set of basic modules consists of a primary module and a number of supporting modules. In this information, only the primary module is discussed.

• The first basic module is the IMS ACBGEN utility, DFSUACB0. Its primary function is to prepare the ACB library for processing, and build a list of PSB names, and pass them, one at a time, to the Block Builder module.
• The second basic module is the Block Builder, DFSDLBL0. Its primary function is to load a PSB and its referenced DBDs and build DLI control blocks. These control blocks are then passed to the Block Mover module.
• The third basic module is Block Mover, DFSUAMB0. Its primary function is to take the DLI control blocks passed to it and build a PSB and one or more DMBs. The PSB is then written into the ACB library. The DMBs might or might not be written into the ACB library.

The Advanced ACBGEN utility replaces the IMS provided DFSUACB0 module and the related supporting modules. However, the DFSDLBL0 Block Builder and DFSUAMB0 Block Mover modules are used to build the PSBs and DMBs.

The Advanced ACBGEN utility builds a list of PSBs. The names of these PSBs are passed to the Block Builder, DFSDLBL0, where they are processed. Statistics and IMS generated messages for each PSB and DMB built are captured. When the PSB list has been processed, several reports are generated that provide a summary list of the ACB library members that have been added, deleted, replaced, or not replaced.

An important feature of Advanced ACBGEN utility is its management and presentation of the DFSnnnn messages generated during the ACBGEN process. The utility presents PSB and DBD information in a concise tabular format rather than the prose format used by the utility provided in IMS. As more PSBs and DBDs are involved in the ACBGEN, the significance of this presentation method increases.

The elapsed time can be reduced by reducing both the number of DASD EXCPs and the CPU time. As more PSBs are generated, the time is reduced, especially when a 'BUILD PSB=ALL' ACB is generated.

Advanced ACBGEN utility JCL is compatible with the IMS utility. The use of Advanced ACBGEN utility, whether it is used alone or called within an ACB Generation and Catalog Populate utility job, can be enabled by adding the load module library that includes the Advanced ACBGEN load modules to the top of the STEPLIB DD concatenation. Additional optional DD statements can be added to request Advanced ACBGEN utility features. These additional DD statements are ignored if they are present when the IMS utility is used.