When I use the allocate command in REXX , I always use ALLOC DDNAME(ddname) , but I found the ALLOC FILE(filename) also work well ,
I read the TSO Command Reference , it seems that there's no difference explanation for Alloc FILE and Alloc DDNAME , anyone knows the difference ? thanks !
FILE(name) | DDNAME(name)
specifies the name to be associated with the data set. It can contain up to eight characters. (This name corresponds to the name on the data definition (DD) statement in job control language and must match the ddname in the data control block (DCB) that is associated with the data set.) For PL/I, this name is the file name in a DECLARE statement and has the form DCL file name FILE; for example, DCL MASTER FILE. For COBOL, this name is the external name used in the ASSIGN TO clause. For FORTRAN, this name is the data set reference number that identifies a data set and has the form FTxxFyyy, for instance, FT06F002.
If you omit this operand, the system assigns an available file name (ddname) from a data definition statement in the procedure that is invoked when you enter the LOGON command.
Do not use special ddnames unless you want to use the facilities those names represent to the system.
For more information about the special ddnames SYSMDUMP, SYSUDUMP, SYSCHK, SYSCKEOV, and SYSABEND see z/OS MVS JCL Reference.
For more information about the special ddnames JOBCAT, JOBLIB, STEPCAT, and STEPLIB see z/OS MVS JCL Reference.
