Can't find specific rules in the documentation on the use of LRECL=. I don't know the record length of this comma delimited text file, I'm trying to read from the mainframe. If I over estimate the record length, ie. LRECL=1900 when it actually is 1850, will that cause a problem when SAS is reading the file?
Anyway, if your file is has a variable length record (delimited), you should specify the RECFM=V (or VB for blocked files) option and estimate LRECL has a value larger than the longest record that your expect to read.
You don't want to code LRECL= for an INFILE (not in mainframe JCL or SAS code) -- specify the INFILE parameter COLUM= and use its value (SAS maintains it) to detect where you are in your record for INPUT handling. As Daniel mentioned, if the file is RECFM=V or VB, your records may be of varying length -- however if the file is RECFM=F or FB, you will need to consider whether or not to use techniques to detect the current non-blank values for your variables -- look at MISSOVER and TRUNCOVER options for INFILE.