If you do not issue a SYSPUNCH or SYSLIN FILEDEF command before the ASMAHL command, the ASMAHL command issues the following FILEDEF commands:

FILEDEF SYSPUNCH PUNCH
FILEDEF SYSLIN DISK fn TEXT m1 (RECFM FB LRECL 80 BLOCK 16000

where fn is the file name specified on the ASMAHL command. If the assembler source file (SYSIN input) is not on disk or is on a read-only disk, the file mode m is set to the first available read/write disk. If the source file is on a read/write disk, the mode letter m is set to the mode of that read/write disk. For example, if the source file is on a read/write B disk, the file mode m1 is set to “B1”.