You should use a file that describe your schema first:
Paste the following in a file 'tree.schema':
======= CUT =====
D -R DEFAULT
D -S DEFAULT
T -S -Bloc=4096
T -S -Lock=40
T -S -Glob=4096
T -S -Alloc=1000
T -S -Ext=3000
T -S -Ac=BG
T -R -Rec=4096
T -R -Key=1019
T -R -N=NEVER
T -R -J=BE
A -S DEFAULT -F="tree-gbl.dat"
A -R DEFAULT -D=DEFAULT
LOC -R=DEFAULT
SH -R DEFAULT
V -A
E
======= CUT =====
Basically, this file destroy DEFAULT template, recreate the DEFAULT template with specific values. Recordsize 4096, keysize 1019...
Then create the segment DEFAULT and point it to tree.db file.
Make the DEFAULT Region to use the DEFAULT SEGMENT that points to tree.db.
Make that LOCK will be stored in the default region.
Then display the DEFAULT region.
Then verify, then exit.
This file should be sent to GDE then mupip:
shell> export gtm_dist=/opt/fis-gtm/V6.3-000A_x86_64/
shell> export gtmgbldir=tree.gld
shell> $gtm_dist/mumps -r ^GDE @tree.schema
shell> $gtm_dist/mupip create
The documentation is available in the Administrator guide and GDE command help.
Hope that it will give you enough hints to get you started.
http://tinco.pair.com/bhaskar/gtm/doc/books/ao/UNIX_manual/gdecmds.html