Sir it is not my place to ask you why you asked a particular question, or why you want to use a particular approach. Your reasons are really none of my business. If the same approach caused problems in our shop I may mention it as a professional courtesy relative to the technical discussion. If people don't think something is worth discussing they don't have to reply.
----- Original Message ----- From: IBM Mainframe Discussion List <IBM-MAIN@bama.ua.edu> To: IBM-MAIN@bama.ua.edu <IBM-MAIN@bama.ua.edu> Sent: Fri Mar 04 19:13:32 2011 Subject: Re: Difference between DISP=NEW and MOD for a PDS member? That could be. JCL apparently converts DISP=MOD to DISP=NEW internally (x'C0' is what ends up in JFCBIND2 for either one). That's why I was asking. They are both supported -- why, I wondered -- is there a difference? I'm not just playing with JCL variations in my spare time. I have responsibility for a "virtualization" product that does a lot of varied processing depending on many details of its execution environment. I have a bug involving the treatment of PDS members DISP=NEW/MOD. I'm trying to figure out what the distinctions are, if any. Face it, the MVS documentation tends to be very scattered. It's tough to know whether the discussion you have found is the only relevant discussion. And it's tough to run an experiment when you don't know what exactly you are looking for. It may be a poor practice in actual coding, but customers/users do what they do. It's supported by IBM. Not good form for a product to fail. And "it's supported by IBM but it's a poor coding practice" is not an argument I want to have with a customer or prospect. BTW, which one is poor coding practice, NEW or MOD? Geez! Why do I have to defend asking a question on IBMMAIN? Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Gerhard Adam Sent: Friday, March 04, 2011 4:57 PM To: IBM-MAIN@bama.ua.edu Subject: Re: Difference between DISP=NEW and MOD for a PDS member? Why should it make a distinction? DISP=MOD and DISP=NEW behave exactly the same way for a new data set also. In fact, a DISP=MOD doesn't make logical sense for a PDS, since it isn't sequential data that is being appended, nor does it make sense for a directory. While the manual indicates that both forms work, they seem like a poor practice in actual coding. -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Charles Mills Sent: Friday, March 04, 2011 4:34 PM To: IBM-MAIN@bama.ua.edu Subject: Re: Difference between DISP=NEW and MOD for a PDS member? Yes. Notice that it makes no distinction between MOD and NEW for a member. That is exactly why I asked the question. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Gerhard Adam Sent: Friday, March 04, 2011 4:08 PM To: IBM-MAIN@bama.ua.edu Subject: Re: Difference between DISP=NEW and MOD for a PDS member? Has it occurred to anyone to just look at the JCL Reference manual? " When you specify DISP=MOD or DISP=NEW for a partitioned data set (PDS) or partitioned data set extended (PDSE), and you also specify a member name in the DSNAME parameter, the member name must not already exist. If the member name already exists, the system terminates the job. When you specify DISP=OLD for a PDS or a PDSE, and you also specify a member name in the DSNAME parameter, the data set must already exist. If the member name already exists and the data set is opened for output, the system replaces the existing member with the new member. If the member name does not already exist and the data set is opened for output, the system adds the member to the data set. When you specify DISP=MOD for a PDS or a PDSE, and you do not specify a member name, the system positions the read/write mechanism at the end of the data set. The system does not make an automatic entry into the directory. When you specify DISP=MOD for a PDS or a PDSE, and you do specify a member name, the system positions the read/write mechanism at the end of the data set. If the member name already exists, the system terminates the job. When you specify DISP=SHR for a partitioned data set extended (PDSE) and also specify a member name, then: * If the member name exists, the member can have one writer or be shared by multiple readers, or * If the member name does not exist, the member can be added to the data set. Thus, multiple jobs can access different members of the data set and add new members to the data set concurrently -- but concurrent update access to a specific member (or update and read by other jobs) is not valid. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
