use tempdb
go
sp_helpsegment "default"
go

Do any of the following 
1. restart the sybase database server
2. alter the size of the tempdb

If your tempdb gets full you can do one of following:
you can expand your tempdb or you can use

select lct_admin(0,2)
go
It will abort all open transactions.But be sure the task by 
confirming with the concern users.
Restarting the server is not recommanded.

lct_admin (0,2) would abort all open transactions, or you 
can go for altering the tempdb space. Multiple tempdb's is 
a feature which can be implemented to minimize such issues 
of tempdb getting full.