specifies the length of the SAS buffers used as I/O areas when DL/I calls are executed. The length must be greater than or equal to the length of the longest segment or path of segments accessed. If LRECL= is not specified, the default buffer length is 1000 bytes.
If a retrieved segment or path of segments is longer than the value of LRECL=, DL/I overlays other data or instruction storage areas. Unpredictable results can occur if this happens.
And the x is the maximum record length for the data in bytes.For input, the actual LRECL value of the file is the default. For output, the default is 132.