Ola's maintenance solution is not processing sysjob* tables I have used Ola Hallengren's script to back up and maintain databases. 

However, it does not perform any reindex or reorganize operations against certain tables in msdb, such as sysjobhistory, even though they have fragmentation above the defined thresholds. Here is the script I am using:

EXECUTE dbo.IndexOptimize
  @Databases = 'SYSTEM_DATABASES',
  @FragmentationLow = NULL,
  @FragmentationMedium = 'INDEX_REORGANIZE,INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE',
  @FragmentationHigh = 'INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE',
  @FragmentationLevel1 = 5,
  @FragmentationLevel2 = 30,
  @UpdateStatistics = 'ALL',
  @OnlyModifiedStatistics = 'Y'
You need an additional parameter to tell Ola's script to consider Microsoft-shipped objects, since those job-related tables in msdb are marked as is_ms_shipped:

@MSShippedObjects = N'Y'


(This parameter defaults to N'N', which means ignore Microsoft-shipped objects, and is documented here.)