I remember (I believe) when DSN=NULLFILE came along. The altering of DD statements in a proc is the whole essence of DSN=NULLFILE. Before NULLFILE came along, if you had a proc with the DD statement
//MYDD DD DSN=&SOMEPRM,... then there was no "parameter" way for the user (caller) to "dummy out" MYDD. Stating it differently, there was no way to code a DD statement inside a proc that based on a user parameter could be either a "real" DSN or DUMMY. DSN=NULLFILE made it possible. I think that is the entire difference between DUMMY and NULLFILE: it's a syntactical difference. It's like languages with more than one way to express (for example) an iterative loop. DUMMY is easier to code, NULLFILE is more flexible, especially in a proc. I don't think the end result is any different. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Paul Gilmartin Sent: Tuesday, May 31, 2005 8:47 AM To: [email protected] Subject: Re: DUMMY and BLKSIZE=0 In a recent note, john gilmore said: > Date: Tue, 31 May 2005 15:16:36 +0000 > > Once written within a procedure neither of the DD statements > > //<ddname> DD DUMMY > > or > > //<ddname> DD DUMMY, . . . > > can be altered into one that in fact is functional, permits non-null > outputs to be written or non-null inputs to be read. > Thanks! I hadn't considered that. Now I'll know better. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
