Since you posted in the COBOL forum, are you planning on combining 50+ files in a COBOL program?
Many times it is NOT a good idea to combine data like this, since the record lengths can help identify the data source. Why do you think you need to create one file out of 50+?
Furthermore, you are quite lacking in details -- are you wanting the output file to be fixed length or variable length? If fixed length, are you using the length of the longest record of the 50+ files or are you planning on truncating some of the records? Do all 50+ files have some form of record identifier to distinguish them, especially if two or more of the files have the same length records? If not, how will you tell the records apart when reading them in the future? Are the record formats all in the same location or do you need to standardize them as part of the copy process? Are all of the record identifiers unique or will have you to change some of them to be unique as you copy the data? How many records are in each file? Are you wanting to combine all 50+ files in one job step or are you running multiple job steps to combine the records -- and if so, what are you using the seperate the various records into job steps? When you say 50+, do you mean 51 or 2521 -- the number of files does make a difference!
And on and on and on ... there are many, many questions you have not even BEGUN to answer before we could provide any assistance.