Why LRECL=0 doesn't work in HIST/FILE ?

For HBOOK/RZ files, the largest record length which can be auto detected is LRECL=8192. Due to an early design mistake the record length is hidden in the second record of an RZ file. This means that, before the record length can be determined, almost LRECL+200 words should be buffered. Increasing this buffer will only push these limit but won't really solve the problem. So for all the files with a record length greater than 8192 the record must be specified explicitly in the command HISTOGRAM/FILE.

The CHAIN command open the chained files with the automatic record length detection (LRECL=0) therefore it is not possible to chain files having a record length greater than 8192 unless the chain is built with //lunxx. Example:

  h/file 20 file_1 16384
  h/file 21 file_2 16384
  h/file 22 file_3 16394  chain chain_1 //lun20 //lun21 //lun22
  cd //chain_1