# S437: End-of-volume error, bad DCB or DEB Source: https://wndsoftware.com/mainframe-errors/s437 ### S437: End-of-volume error, bad DCB or DEB An S437 abend means end-of-volume processing failed because the control blocks it was given weren't valid. 437-08 means the DCB pointer was wrong when the program issued FEOV, and 437-0C means the data set's DEB wasn't in the DEB table. Message IEC025I gives the return code. #### Other names for this code Also written as `437`, `S437-08`, `S437-0C`, `abend 437`, `system abend 437`, `437-0C`, `IEC025I 437`. ### What it means FEOV (force end of volume) is an assembler macro. It tells the system to stop using the current volume of a sequential data set and move to the next one, as if the end of the volume had been reached. The system then runs its normal end-of-volume (EOV) routine. To do that it needs a valid DCB for an open data set, and the data extent block (DEB) that OPEN built for that DCB. End-of-volume processing also runs without FEOV, whenever a GET, PUT, READ or WRITE reaches the end of a volume, and it needs the same control blocks then. If either check fails, the system issues message IEC025I and ends the step with system completion code 437. - `437-08` means the DCB pointer wasn't valid when FEOV was issued. - `437-0C` means the DEB wasn't in the DEB table. IBM doesn't tie this one to FEOV, so it can come from any end-of-volume. The system keeps a table of the DEBs that belong to open data sets. A DEB that isn't in it doesn't belong to an open data set the system knows about. Both point to a program problem rather than a problem with the data or the volume. IBM treats S437 as a probable user error. You're most likely to meet it in assembler code, or in a product that drives its own tape or volume switching. ### Common causes - The program passed the wrong address on FEOV, such as the address of a work area, a copy of the DCB, or a register that no longer held the DCB address (437-08). - The DCB's pointer to its DEB no longer points to a DEB the system knows, for example because the DCB was overwritten or reused after another OPEN and CLOSE (437-0C). - A storage overlay damaged the DCB before FEOV or the next read or write reached end of volume. - A vendor product issued FEOV under conditions it didn't expect, and maintenance for it fixes the problem. ### How to find the problem - Find IEC025I in the job log. It has the form `IEC025I 437-rc,mod,jobname,stepname,ddname,dev,volser,dsname`. Note the return code and the DD name. - In the dump, find the address the program passed to FEOV and check that it points to the DCB for that DD, and that the DCB is still open. - Read through the program for paths that CLOSE the DCB and can still reach FEOV, or that reuse the register holding the DCB address. - If a product issued the FEOV, search its support site for the abend and keep the dump for the vendor. ### How to fix it - Pass the address of the real, open DCB to FEOV. - Make sure FEOV, and any read or write, can only be reached while the data set is open. - Find and fix any storage overlay that changes the DCB. - If the abend comes from a product, apply its maintenance or open a problem with the vendor. ### What it looks like ```text IEC025I 437-0C,IGC0003A,PAYRUN01,STEP060,TAPEOUT,0B41,PR4417,PROD.PAYROLL.ARCHIVE IEA995I SYMPTOM DUMP OUTPUT SYSTEM COMPLETION CODE=437 REASON CODE=0000000C IEF450I PAYRUN01 STEP060 - ABEND=S437 U0000 REASON=0000000C ``` ### IBM documentation [IBM z/OS: 437](https://www.ibm.com/docs/en/zos/3.1.0?topic=codes-437). Use the documentation for your installed release. [Report a correction to WND Software](https://wndsoftware.com/contact#message). Technical reviewer: [Albert Joseph](https://wndsoftware.com/authors/albert-joseph), WND Software. Last reviewed 2026-10-18 by the WND Software team. Written in our own words. For the full reference, check IBM’s z/OS documentation for your release. ### Related codes [S837 End-of-volume error, often too few volumes Read →](https://wndsoftware.com/mainframe-errors/s837) [S737 End-of-volume or concatenation error Read →](https://wndsoftware.com/mainframe-errors/s737) [S0C4 Protection exception Read →](https://wndsoftware.com/mainframe-errors/s0c4) [S001 I/O error Read →](https://wndsoftware.com/mainframe-errors/s001) ### Questions #### What is FEOV? FEOV is the force end-of-volume macro. A program issues it to stop using the current volume and continue on the next one without closing the data set. #### Can bad data cause S437? Not usually. It's raised when the control blocks for the data set aren't valid, which points to the program or a storage overlay rather than the contents of the file. [z/OS system abends](https://wndsoftware.com/mainframe-errors/zos-abends) · [S413](https://wndsoftware.com/mainframe-errors/s413) · [S522](https://wndsoftware.com/mainframe-errors/s522) [← All error codes](https://wndsoftware.com/mainframe-errors/)