Abend code 999 (or X'3E7')
This abend is issued for the following reasons:
* No function pool is established for a command processor.
For example, a command processor that uses ISPF services is invoked using option 6 or SELECT CMD, but the command processor does not have a function pool. The user needs to have an entry for the command processor in the ISPTCM with the X'40' flag set on. The X'40' flag indicates that the command requires a function pool. Refer to ISPF Planning and Customizing for more information on customizing the ISPTCM.
* An error occurs while another error is already being processed.
ISPF issues the abend code 999 in this case to protect against an infinite loop.
* An error occurred during ISPF initialization.
o An I/O error occurred due to ISPF library allocations such as ISPSLIB, ISPPLIB, ISPMLIB, and so forth, containing inconsistent or incorrect DCB attributes.
o An ISPF library allocation does not contain the required ISPF libraries in its concatenation. For example, the ISPMLIB contains user product libraries but not ISPF libraries.
I found that the ISPF profile dataset was full after trying to save some changes.
Compressed the ISPF dataset and then redoing the operation fixed that issue.
Increasing the ISPF dataset was performed by a colleague, once I logged off - to prevent / minimise the issue from reoccurring in the future.
The issue has not occurred since - so far so good.