0602-101 error on large files using vi command

http://www-01.ibm.com/support/docview.wss?uid=isg3T1012365

Problem(Abstract)
When using the vi editor to open a large file, it prints error:
ex: 0602-101 Out of memory saving lines for undo


Cause
The -y option of 'vi' can be used to override the maximum line setting of 1,048,560 with any value greater than 1024.

Resolving the problem
Example:
When opening 20 MB file with vi, the error received is:

0602-101 out of memory for undo.

Check the following first:

1. Check free space in /tmp and /var filesystems
2. Check that user file limit (ulimit -f) is set to unlimited

If items 1 and 2 above do not correct the problem, continue with the following steps:

1) run wc -l file-to-edit to the get the number of lines (nl) in the file.
2) use the following calculation to determine the value specified in the -y <nnl> option nnl = (nl + 1) * 2
3) vi -ynnl file-to-edit
4) If #3 still fails it may be necessary to set the following variable and then do #3 again.
export EXINIT='set dir=/largefilesystem'