* Dollar jumps 1.2 pct to 94.20 yen
* BOJ says to double monetary base in 2 years
* BOJ's Unanimous decision on many policy steps seen as positive for dlr/yen
* ECB & BOE policy meetings also eyed
By Hideyuki Sano
TOKYO, April 4 (Reuters) - The yen dropped sharply on Thursday after the Bank of Japan announced aggressive easing, saying it will double its holdings of bonds and stocks in two years.
The BOJ also said it would extend the average maturity of bonds it holds to around seven years from around three years now, dashing suspicions that it could underdeliver as it had often in the past.
"All the menu the market has been talking has been delivered so the market welcomed the decision," said Teppei Ino, currency analyst the Bank of Tokyo-Mitsubishi UFJ.
The dollar jumped 1.2 percent to 94.21 yen, pulling away from a one-month low of 92.57 hit on Tuesday, though it is still off a 3-1/2 year peak of 96.71 set a few weeks ago.
THe BOJ also pledged more buying of riskier assets such as equity exchange traded funds (ETFs).
The dollar had come under pressure overnight after disappointing U.S. private sector jobs data, which prompted traders to ratchet down their expectations for Friday's payrolls data.
In addition, U.S. service sector growth fell to the slowest in seven months, denting recent optimism on the U.S. economy.
ECB AND BOE
Also in focus later in the day are policy meetings of the European Central Bank and Bank of England.
Neither central bank is expected to deliver any new stimulus for now, although the ECB is likely to try and calm markets by pledging to keep the banking system lubricated after Cyprus's brush with financial meltdown.
Still the risk of any surprises, such as an interest rate cut from the ECB or a restart of the BOE's bond-buying programme, is keeping investors wary of the euro and sterling.
The euro was at $1.2845, flat on the day but not far from a four-month trough of $1.2750 plumbed on March 27. Sterling was little changed at $1.5130, having dipped to a two-week low of $1.5075 on Wednesday.
The Australian dollar briefly gained to as high as $1.0495 , near its 10-week high of $1.0498 hit on Wednesday, on surprise strength Australian retail sales. But it last stood flat at $1.0453 as option-related offers at $1.05 were blocking the currency's further advance.