Database Analyzer BIT MAP FREE BLKS displays 0 free blks

Products

• Database Analyzer for IMS for z/OS

Issue/Introduction

Database Analyzer displays BIT MAP FREE BLKS as 0 in the Data Base Block Information report even though there are free blocks.

DATA BASE BLOCK INFORMATION                               
___________________________                               
  NUMBER OF BIT MAP BLKS                     1          
  NUMBER OF FULL BLKS                          0          
  NUMBER OF BLKS WITH SPACE           125          
                                         _______          
  TOTAL # OF BLKS IN DSG.                    126          
  BIT MAP FREE BLKS                                0  -   0.0% 

 

Resolution

Each bit in a bitmap describes whether enough space is available in a block to hold the longest segment defined in the data set group.

So there might still be free space in the block (as indicated by ‘NUMBER OF BLKS WITH SPACE’) but potentially not enough to hold the longest segment. BIT MAP FREE BLKS will display 0 if none of these are large enough to hold the longest segment in the DSG.