Joined: 06 Jun 2008 Posts: 8151 Location: East Dubuque, Illinois, USA
There is a link to the manuals at the top of the page. It does not take long to go into the JCL Language Reference manual and do a search on concatenation to find
220.127.116.11 Logical Record Lengths for Concatenated Data Sets
Concatenated data sets with format-V records can have different logical record lengths as long as the data set with the largest logical record length appears first in the concatenation. (Note that you can state a value equal to the largest logical record length for LRECL on the first DD statement, regardless of what the actual logical record length of this data set is.)
You do not say if your records are variable length (which is a requirement to concatenate different length records) or fixed length (which is not allowed and requires you to change your approach).