If a pseudo-device, pipe, or character special file is connected for formatted or unformatted sequential access with no RECL= specifier, or for formatted stream access, the default record length is 32 768 rather than 2 147 483 647, which is the default for sequential-access files connected to random-access devices. (See the default_recl run-time option.)
In certain cases, the default maximum record length for formatted files is
larger, to accommodate programs that write long records to standard
output. If a unit is connected to a terminal for formatted sequential
access and there is no explicit RECL= qualifier in the OPEN
statement, the program uses a maximum record length of
2 147 483 646 (2**31-2) bytes, rather than the usual default of 32 768
bytes. When the maximum record length is larger, formatted I/O has one
restriction: WRITE statements that use the T or
TL edit descriptors must not write more than 32 768
bytes. This is because the unit's internal buffer is flushed each
32 768 bytes, and the T or TL edit descriptors
will not be able to move back past this boundary.