IRRUT400 formats and initializes each output data set with an ICB, templates, segment table, BAM blocks, a complete index structure, profiles, and an alias index from the input database. It also provides the following features:

• Index compression: IRRUT400 builds the index structure of each output data set from the lowest level upwards. Because no block splitting occurs, the index structure is automatically compressed. You can specify a percentage of free space to be left in each index block.
• Block alignment: You can request that RACF® attempt to keep any segment that is not larger than one block (4KB) within a block boundary.
• Index structure correction: The utility uses only the sequence-set index blocks of the input data sets; it builds the output index-structure from the sequence set. As a result, inconsistencies in higher-level index blocks are corrected and do not prevent the utility from executing correctly.
• Multiple input data sets: When running with more than one input data set, IRRUT400 copies the ICB, templates, and segment table from the lowest number INDDn data set that you specify in your JCL.